Reversible, chemically or environmentally responsive polymers, and coatings containing such polymers

ABSTRACT

We have demonstrated reversibly reducing metal-ion crosslinkages in polymer systems, by harnessing light, creating a dynamic and reversible bond. The reduction induces chemical and physical changes in the polymer materials. Some variations provide a polymer composition comprising: a polymer matrix containing one or more ionic species; one or more photosensitizers; and one or more metal ions capable of reversibly changing from a first oxidation state to a second oxidation state when in the presence of the photosensitizers and light. Some embodiments employ urethane-based ionomers capable of changing their crosslinked state under the influence of a change in counterion valance, using light or chemical reducing agents. This invention provides films, coatings, or objects that are reversible, re-mendable, self-healing, mechanically adjustable, and/or thermoplastic/thermoset-switchable.

PRIORITY DATA

This patent application is a non-provisional application claimingpriority to U.S. Provisional Patent App. No. 62/271,942, filed on Dec.28, 2015, which is hereby incorporated by reference herein. This patentapplication is also a continuation-in-part application of U.S. patentapplication Ser. No. 15/073,610, filed on Mar. 17, 2016, which claimspriority to U.S. Provisional Patent App. No. 62/269,366, filed on Dec.18, 2015, and to U.S. Provisional Patent App. No. 62/269,984, filed onDec. 19, 2015, each of which is hereby incorporated by reference herein.

FIELD OF THE INVENTION

The present invention generally relates to polymers with reversibleproperties, and methods of making and using these polymers.

BACKGROUND OF THE INVENTION

Historically, improvements to polymer properties have focused on staticproperties including strength, thermostability, toughness, anddurability. Recent research has broadened to incorporatemultifunctionality into polymers that can adapt to their environment,with dynamic properties such as recyclability, remoldability,self-healing, and shape memory. The ability to rework and remold certainpolymers is of great interest due to increased awareness of recycling,high cost of materials, and the ability to extend the life of a materialthrough in situ repair.

In order to accomplish many of these properties, it is necessary to formand break bonds or crosslinks. Research in reversible crosslinkingwithin materials dates back to the 1960s, where the majority of the workwas based on thermally triggered Diels-Alder chemistry. New approachesare needed that provide greater flexibility in trigger mechanisms andstrategies for reversibility.

There are two classes of polymer materials that are categorized based ontheir network structure: thermosets and thermoplastics. Thermosets arepolymers that are heated, molded, and cured to form a permanent shapeand can no longer be reworked due to network constraints when cured.Thermoplastics will soften upon heating, becoming flowable, which allowsthem to be remolded multiple times without loss of properties. Thebiggest distinction between the two classes is the crosslinkingarchitecture of the network. Thermosets tend to have a high density ofcrosslinking—specifically, interchain covalent bonds—that hold all thepolymer chains together. By contrast, thermoplastics are made upprimarily of long individual polymer chains that associate together toform a network. This architecture gives thermosets high thermalstability, high rigidity, dimensional stability, and resistance todeformation, which makes them desirable, but removes the ability torecycle, reshape, and repair. Remolding and reshaping thermoplastics ismade possible due to non-covalent associations between the polymerchains; however, the reduced number of crosslinks makes the materialmore vulnerable to creep under stress.

Introducing reversible crosslinking into a polymer network cancontrollably capture the advantages of both a thermoset andthermoplastic. A conventional problem with crosslinking a network isthat the material becomes non-recyclable and non-formable. However, ifthese crosslinks could be removed, the desirable properties of athermoplastic—remolding and shaping—are made possible.

While thermally reversible crosslinking by Diels-Alder chemistry hasbeen researched, uniform heating is generally difficult to achieve forlarge parts. Moreover, the response is slow and gradual, due to the lowthermal conductivity of polymers as well as the bond breakage thatoccurs over a wide temperature range. Polymer materials instead can besynthesized to be responsive to mechanics. Mechanoresponsive materialsrely on ultrasonication or other means of mechanical stress to breakcrosslinking chains. Large material parts would suffer from energytransfer challenges. Reversibility of such systems relies on there-equilibration of the components with time, a slow and undesirableprocess. Polymer materials instead can be synthesized to be responsiveto electricity. Electroresponsive materials are triggered by anelectrical potential that often oxidizes or reduces components.

In view of the shortcomings in the art, what is desired is non-thermalreversible crosslinking for mechanical tunability and self-healingproperties, preferably exploiting naturally occurring stimuli, such asnatural light. Coating technologies based on these reversible polymerswould enable improved coating materials and systems. Compositionssuitable for these coating systems are also needed.

SUMMARY OF THE INVENTION

The present invention addresses the aforementioned needs in the art, aswill now be summarized and then further described in detail below.

Some variations provide a polymer composition comprising:

(a) a polymer matrix containing one or more ionic species;

(b) one or more photosensitizers; and

(c) one or more metal ions capable of reversibly changing from a firstoxidation state to a second oxidation state when in the presence of thephotosensitizers and light,

wherein the metal ions, in the first oxidation state, have a firstcoordination number with the ionic species,

wherein the metal ions, in the second oxidation state, have a secondcoordination number with the ionic species, and

wherein the first coordination number is greater than the secondcoordination number.

In some embodiments, the second oxidation state is one unit of chargeless than the first oxidation state. In certain embodiments, the secondoxidation state is two or more units of charge less than the firstoxidation state.

The metal ions may be selected from the group consisting of ions of Ni,Fe, Cu, Hg, Cd, and combinations thereof, for example.

The photosensitizers may include at least one organic photosensitizer,such as (but not limited to) a photosensitive organic dyes.

Alternatively, or additionally, the photosensitizers may include atleast one inorganic photosensitizer, such as (but not limited to)photosensitive inorganic dyes, metal oxides, semiconductors, andcombinations thereof.

In some embodiments of the invention, the polymer matrix contains asubstantially continuous matrix containing a first component; and,dispersed within the matrix, a plurality of inclusions containing asecond component that is chemically different than the first component,wherein one of the first component or the second component is a firstpolymer having a surface energy between about 5 mJ/m² to about 50 mJ/m²,and the other of the first component or the second component is a secondpolymer containing the one or more ionic species, and wherein the firstpolymer and the second polymer are chemically connected ionically orcovalently.

The first polymer may be a fluoropolymer selected from the groupconsisting of polyfluoroethers, perfluoropolyethers,polyfluoroacrylates, polyfluorosiloxanes, and combinations thereof. Insome embodiments, the fluoropolymer is

wherein:

-   X=CH₂—(O—CH₂—CH₂)_(p)—OH wherein p=0 to 50;-   m=1 to 100; and-   n=1 to 100.

The second polymer may be selected from the group consisting ofpolyethers, polyesters, polysiloxanes, polyelectrolytes, andcombinations thereof. In some embodiments, the second polymer includes amaterial selected from the group consisting of poly(acrylic acid),poly(ethylene glycol), poly(2-hydroxyethyl methacrylate), poly(vinylimidazole), poly(2-methyl-2-oxazoline), poly(2-ethyl-2-oxazoline),poly(vinylpyrolidone), cellulose, modified cellulose, carboxymethylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methylcellulose, hydrogels, PEG diacryalate, monoacrylate, and combinationsthereof.

The ionic species includes one or more species selected from the groupconsisting of an ionizable salt, an ionizable molecule, a zwitterioniccomponent, a polyelectrolyte, an ionomer, and combinations thereof, invarious embodiments.

In certain embodiments, the ionic species is selected from the groupconsisting of (2,2-bis-(1-(1-methyl imidazolium)-methylpropane-1,3-diolbromide), 1,2-bis(2′-hydroxyethyl)imidazolium bromide,(3-hydroxy-2-(hydroxymethyl)-2-methylpropyl)-3-methyl-1H-3λ⁴-imidazol-1-iumbromide, 2,2-bis(hydroxymethyl)butyric acid,N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid,N-methyl-2,2′-iminodiethanol, 3-dimethylamino-1,2-propanediol,2,2-bis(hydroxymethyl)propionic acid, 1,4-bis(2-hydroxyethyl)piperazine,2,6-diaminocaproic acid, N,N-bis(2-hydroxyethyl)glycine,2-hydroxypropanoic acid hemicalsium salt, dimethylolpropionic acid,N-methyldiethanolamine, N-ethyldiethanolamine, N-propyldiethanolamine,N-benzyldiethanolamine, N-t-butyldiethanolamine, bis(2-hydroxyethyl)benzylamine, bis(2-hydroxypropyl) aniline, and homologues, combinations,derivatives, or reaction products thereof.

In some embodiments, the second polymer consists essentially of theionic species (i.e., the second polymer is the ionic species).

In some embodiments, the first polymer and the second polymer arecovalently connected in a block copolymer.

The polymer composition may further contain one or more additionalcomponents selected from the group consisting of a particulate filler, asubstrate adhesion promoter, a pigment, a coloring agent, a plasticizer,a flattening agent, and a flame retardant.

The polymer composition according to some embodiments contains, in thepolymer matrix or as another component, a segmented copolymercomprising:

one or more soft segments selected from fluoropolymers having an averagemolecular weight from about 500 g/mol to about 20,000 g/mol, wherein thefluoropolymers are (α,ω)-hydroxyl-terminated and/or(α,ω)-amine-terminated, and either: (i) wherein the soft segmentscontain the one or more ionic species; or (ii) one or more copolymerchains that are distinct from the soft segments, wherein the copolymerchains contain the one or more ionic species;

one or more isocyanate species, or a reacted form thereof, possessing anisocyanate functionality of 2 or greater; and

one or more polyol or polyamine chain extenders or crosslinkers, or areacted form thereof.

The fluoropolymers may be selected from the group consisting ofpolyfluoroethers, perfluoropolyethers, polyfluoroacrylates,polyfluorosiloxanes, and combinations thereof.

The segmented copolymer further may include one or more second softsegments selected from polyesters or polyethers, wherein the polyestersor polyethers are (α,ω)-hydroxyl-terminated and/or(α,ω)-amine-terminated. The polyesters or polyethers may be selectedfrom the group consisting of poly(oxymethylene), poly(ethylene glycol),poly(propylene glycol), poly(tetrahydrofuran), poly(glycolic acid),poly(caprolactone), poly(ethylene adipate), poly(hydroxybutyrate),poly(hydroxyalkanoate), and combinations thereof.

Within the segmented copolymer, the ionic species may include one ormore species selected from the group consisting of an ionizable salt, anionizable molecule, a zwitterionic component, a polyelectrolyte, anionomer, and combinations thereof. In certain embodiments, the ionicspecies is selected from the group consisting of (2,2-bis-(1-(1-methylimidazolium)-methylpropane-1,3-diol bromide),1,2-bis(2′-hydroxyethyl)imidazolium bromide,(3-hydroxy-2-(hydroxymethyl)-2-methylpropyl)-3-methyl-1H-3λ⁴-imidazol-1-iumbromide, 2,2-bis(hydroxymethyl)butyric acid,N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid,N-methyl-2,2′-iminodiethanol, 3-dimethylamino-1,2-propanediol,2,2-bis(hydroxymethyl)propionic acid, 1,4-bis(2-hydroxyethyl)piperazine,2,6-diaminocaproic acid, N,N-bis(2-hydroxyethyl)glycine,2-hydroxypropanoic acid hemicalsium salt, dimethylolpropionic acid,N-methyldiethanolamine, N-ethyldiethanolamine, N-propyldiethanolamine,N-benzyldiethanolamine, N-t-butyldiethanolamine, bis(2-hydroxyethyl)benzylamine, bis(2-hydroxypropyl) aniline, and homologues, combinations,derivatives, or reaction products thereof.

Within the segmented copolymer, the isocyanate species may be selectedfrom the group consisting of 4,4′-methylenebis(cyclohexyl isocyanate),hexamethylene diisocyanate, cycloalkyl-based diisocyanates,tolylene-2,4-diisocyanate, 4,4′-methylenebis(phenyl isocyanate),isophorone diisocyanate, and combinations or derivatives thereof.

The polyol or polyamine chain extenders or crosslinkers may have anaverage functionality of at least 3. In some embodiments, the polyol orpolyamine chain extenders or crosslinkers are selected from the groupconsisting of 1,3-butanediol, 1,4-butanediol, 1,3-propanediol,1,2-ethanediol, diethylene glycol, triethylene glycol, tetraethyleneglycol, propylene glycol, dipropylene glycol, tripropylene glycol,neopentyl glycol, 1,6-hexane diol, 1,4-cyclohexanedimethanol, ethanolamine, diethanol amine, methyldiethanolamine, phenyldiethanolamine,glycerol, trimethylolpropane, 1,2,6-hexanetriol, triethanolamine,pentaerythritol, ethylenediamine, 1,3-propanediamine, 1,4-buatendiamine,diethyltoluenediamine, dimethylthiotoluenediamine, isophoronediamine,diaminocyclohexane, N,N,N′,N′-tetrakis (2-hydroxypropyl)ethylenediamine, and homologues, combinations, derivatives, or reactionproducts thereof.

Other variations of the invention provide a polymer compositioncomprising:

(a) a polymer matrix containing one or more ionic species;

(b) one or more chemical reducing agents capable of causing metalreduction; and

(c) one or more metal ions capable of reversibly changing valence from afirst oxidation state to a second oxidation state when in the presenceof the chemical reducing agents,

wherein the metal ions, in the first oxidation state, have a firstcoordination number with the ionic species,

wherein the metal ions, in the second oxidation state, have a secondcoordination number with the ionic species, and

wherein the first coordination number is greater than the secondcoordination number.

Variations of the invention provide a reversibly crosslinkable polymercomposition comprising:

(a) a polymer matrix containing one or more ionic species; and

(b) one or more metal ions characterized in that the metal ions (i)change valence from a first oxidation state to a second oxidation statewhen in the presence of a reducing agent, and (ii) change valence fromthe second oxidation state back to the first oxidation state when in thepresence of an oxidizing agent,

wherein the metal ions, in the first oxidation state, have a firstcoordination number with the ionic species,

wherein the metal ions, in the second oxidation state, have a secondcoordination number with the ionic species,

wherein the first coordination number is greater than the secondcoordination number, and

wherein the polymer composition has a higher crosslink density at thefirst coordination number than at the second coordination number.

Variations of the invention provide films, coatings, or objectscontaining any of the disclosed polymer compositions. The film, coating,or object may be characterized as reversible, re-mendable, self-healing,mechanically adjustable, and/or thermoplastic/thermoset-switchable, invarious embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the structure of some variations of the invention.

FIG. 2 shows a schematic of the reduction of metal ions from a +2 chargeto a +1 charge, where the metal ions bind with negatively chargedfunctional groups present in a polymer network.

FIG. 3 includes a table of experimental data of coating samples fromExamples A-F described herein.

FIG. 4 shows UV-Vis spectrum of the reduction of Fe³⁺ to Fe²⁺ in thepresence of ruthenium dye and light, in Example G.

FIG. 5 shows a graph of storage modulus versus temperature in Example H,demonstrating a full cycle of reversible crosslinking using Ca²⁺ as amodel metal ion.

FIG. 6 shows the stress required for 30% elongation whencharged-constituent-containing polymer films are crosslinked with Cu²⁺ions and after chemical and light reduction, in Example I.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The materials, compositions, structures, systems, and methods of thepresent invention will be described in detail by reference to variousnon-limiting embodiments.

This description will enable one skilled in the art to make and use theinvention, and it describes several embodiments, adaptations,variations, alternatives, and uses of the invention. These and otherembodiments, features, and advantages of the present invention willbecome more apparent to those skilled in the art when taken withreference to the following detailed description of the invention inconjunction with the accompanying drawings.

As used in this specification and the appended claims, the singularforms “a,” “an,” and “the” include plural referents unless the contextclearly indicates otherwise. Unless defined otherwise, all technical andscientific terms used herein have the same meaning as is commonlyunderstood by one of ordinary skill in the art to which this inventionbelongs.

Unless otherwise indicated, all numbers expressing conditions,concentrations, dimensions, and so forth used in the specification andclaims are to be understood as being modified in all instances by theterm “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in the following specification andattached claims are approximations that may vary depending at least upona specific analytical technique.

The term “comprising,” which is synonymous with “including,”“containing,” or “characterized by” is inclusive or open-ended and doesnot exclude additional, unrecited elements or method steps. “Comprising”is a term of art used in claim language which means that the named claimelements are essential, but other claim elements may be added and stillform a construct within the scope of the claim.

As used herein, the phrase “consisting of” excludes any element, step,or ingredient not specified in the claim. When the phrase “consists of”(or variations thereof) appears in a clause of the body of a claim,rather than immediately following the preamble, it limits only theelement set forth in that clause; other elements are not excluded fromthe claim as a whole. As used herein, the phrase “consisting essentiallyof” limits the scope of a claim to the specified elements or methodsteps, plus those that do not materially affect the basis and novelcharacteristic(s) of the claimed subject matter.

With respect to the terms “comprising,” “consisting of,” and “consistingessentially of,” where one of these three terms is used herein, thepresently disclosed and claimed subject matter may include the use ofeither of the other two terms. Thus in some embodiments not otherwiseexplicitly recited, any instance of “comprising” may be replaced by“consisting of” or, alternatively, by “consisting essentially of.”

Variations of the present invention are premised on the incorporation ofions into polymers to alter polymer mechanical properties, such as themodulus and flexibility of these materials. The polymers may be presentin coatings, for example. In some embodiments, ionizable substituentsare combined with fluorinated polymers and hygroscopic polymers toobtain films or coatings with low friction coefficients. The coatingresponse to humidity may be adjusted by controlling the ionization ofthe coating.

In some embodiments of the present invention, charged functional groupsare incorporated into a polymer network, wherein the charged functionalgroups are capable of binding to metal ions. As the metal-ion chargeincreases, multiple functional groups can bind to a single ion, therebyacting as crosslinks within the polymer network. Ionic crosslinking withmetal species of valence charges >1 is demonstrated herein, showing areversible change in mechanical properties by reducing the metal specieschemically or with light, not by heating/cooling the polymer.

Some embodiments employ photosensitizers in coatings. Some embodimentsemploy polymeric ionomers. Some embodiments combine photosensitizerswith polymeric ionomers, to effect a light-mediated chemical and/ormechanical transition. The chemical and/or mechanical transition cangive an anti-corrosion effect, an anti-fouling effect, a “self-healing”effect (also known as “re-mendability”), and/or switchability betweenmechanical properties associated with thermoplastic and thermosetplastics, for example.

Some variations provide a polymer composition comprising:

(a) a polymer matrix containing one or more ionic species;

(b) one or more photosensitizers; and

(c) one or more metal ions capable of reversibly changing from a firstoxidation state to a second oxidation state when in the presence of thephotosensitizers and light,

wherein the metal ions, in the first oxidation state, have a firstcoordination number with the ionic species,

wherein the metal ions, in the second oxidation state, have a secondcoordination number with the ionic species, and

wherein the first coordination number is greater than the secondcoordination number.

The “coordination number” of a metal ion refers to the number of otheratoms to which it is bonded, regardless of type of bond (single versusdouble bond, covalent versus ionic bond, etc.). Thus, the firstcoordination number being higher than the second coordination numbermeans that the metal ions have bonds to more individual ionic species inthe first oxidation state, compared to the second oxidation state. Thisis illustrated in FIG. 2, with the first oxidation state and firstcoordination number on the left-hand side and the second oxidation stateand second coordination number on the right-hand side.

A “photosensitizer” is a molecule that produces a chemical change inanother molecule in a photochemical process induced by light. Thephotosensitizers may include at least one organic photosensitizer, suchas (but not limited to) photosensitive organic dyes, e.g.tris(bipyridine)ruthenium(II) ([Ru(bpy)3]²⁺) chloride or methylene blue.

Alternatively, or additionally, the photosensitizers may include atleast one inorganic photosensitizer, such as (but not limited to)photosensitive inorganic dyes, metal oxides, or semiconductors. Anexemplary inorganic photosensitizer is titanium dioxide.

The metal ions may be selected from alkali metals, alkaline earthmetals, transition metals (including Cd, Zn, and Hg), or post-transitionmetals. The metal ions may be selected from the group consisting of ionsof Ni, Fe, Cu, Hg, Cd, Ca, and combinations thereof, for example.

In some embodiments, the second oxidation state is one unit of chargeless than the first oxidation state. In certain embodiments, the secondoxidation state is two, three, or more units of charge less than thefirst oxidation state. A range of oxidation states may be present, inwhich case the average second oxidation state may be about 0.5, 1.0,1.5, 2.0, 2.5, 3.0, or more units of charge less than the average firstoxidation state.

In some embodiments of the invention, the polymer matrix contains asubstantially continuous matrix containing a first component; and,dispersed within the matrix, a plurality of inclusions containing asecond component that is chemically different than the first component,wherein one of the first component or the second component is a firstpolymer having a surface energy between about 5 mJ/m² to about 50 mJ/m²,and the other of the first component or the second component is a secondpolymer containing the one or more ionic species, and wherein the firstpolymer and the second polymer are chemically connected ionically orcovalently.

The first polymer may be a fluoropolymer selected from the groupconsisting of polyfluoroethers, perfluoropolyethers,polyfluoroacrylates, polyfluorosiloxanes, and combinations thereof. Insome embodiments, the fluoropolymer is

wherein:

-   X=CH₂—(O—CH₂—CH₂)_(p)—OH wherein p=0 to 50;-   m=1 to 100; and-   n=1 to 100.

The second polymer may be selected from the group consisting ofpolyethers, polyesters, polysiloxanes, polyelectrolytes, andcombinations thereof. In some embodiments, the second polymer includes amaterial selected from the group consisting of poly(acrylic acid),poly(ethylene glycol), poly(2-hydroxyethyl methacrylate), poly(vinylimidazole), poly(2-methyl-2-oxazoline), poly(2-ethyl-2-oxazoline),poly(vinylpyrolidone), cellulose, modified cellulose, carboxymethylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methylcellulose, hydrogels, PEG diacryalate, monoacrylate, and combinationsthereof.

The ionic species includes one or more species selected from the groupconsisting of an ionizable salt, an ionizable molecule, a zwitterioniccomponent, a polyelectrolyte, an ionomer, and combinations thereof, invarious embodiments.

In certain embodiments, the ionic species is selected from the groupconsisting of (2,2-bis-(1-(1-methyl imidazolium)-methylpropane-1,3-diolbromide), 1,2-bis(2′-hydroxyethyl)imidazolium bromide,(3-hydroxy-2-(hydroxymethyl)-2-methylpropyl)-3-methyl-1H-3λ⁴-imidazol-1-iumbromide, 2,2-bis(hydroxymethyl)butyric acid,N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid,N-methyl-2,2′-iminodiethanol, 3-dimethylamino-1,2-propanediol,2,2-bis(hydroxymethyl)propionic acid, 1,4-bis(2-hydroxyethyl)piperazine,2,6-diaminocaproic acid, N,N-bis(2-hydroxyethyl)glycine,2-hydroxypropanoic acid hemicalsium salt, dimethylolpropionic acid,N-methyldiethanolamine, N-ethyldiethanolamine, N-propyldiethanolamine,N-benzyldiethanolamine, N-t-butyldiethanolamine, bis(2-hydroxyethyl)benzylamine, bis(2-hydroxypropyl) aniline, and homologues, combinations,derivatives, or reaction products thereof.

In some embodiments, the second polymer consists essentially of theionic species. That is, the second polymer may be ionic and function asthe ionic species.

In some embodiments, the first polymer and the second polymer arecovalently connected in a block copolymer.

The polymer composition may further contain one or more additionalcomponents selected from the group consisting of a particulate filler, asubstrate adhesion promoter, a pigment, a coloring agent, a plasticizer,a flattening agent, and a flame retardant.

The polymer composition according to some embodiments contains, in thepolymer matrix or as another component, a segmented copolymercomprising:

one or more soft segments selected from fluoropolymers having an averagemolecular weight from about 500 g/mol to about 20,000 g/mol, wherein thefluoropolymers are (α,ω)-hydroxyl-terminated and/or(α,ω)-amine-terminated, and either: (i) wherein the soft segmentscontain the one or more ionic species; or (ii) one or more copolymerchains that are distinct from the soft segments, wherein the copolymerchains contain the one or more ionic species;

one or more isocyanate species, or a reacted form thereof, possessing anisocyanate functionality of 2 or greater; and

one or more polyol or polyamine chain extenders or crosslinkers, or areacted form thereof.

The fluoropolymers may be selected from the group consisting ofpolyfluoroethers, perfluoropolyethers, polyfluoroacrylates,polyfluorosiloxanes, and combinations thereof.

The segmented copolymer further may include one or more second softsegments selected from polyesters or polyethers, wherein the polyestersor polyethers are (α,ω)-hydroxyl-terminated and/or(α,ω)-amine-terminated. The polyesters or polyethers may be selectedfrom the group consisting of poly(oxymethylene), poly(ethylene glycol),poly(propylene glycol), poly(tetrahydrofuran), poly(glycolic acid),poly(caprolactone), poly(ethylene adipate), poly(hydroxybutyrate),poly(hydroxyalkanoate), and combinations thereof.

Within the segmented copolymer, the ionic species may include one ormore species selected from the group consisting of an ionizable salt, anionizable molecule, a zwitterionic component, a polyelectrolyte, anionomer, and combinations thereof. In certain embodiments, the ionicspecies is selected from the group consisting of (2,2-bis-(1-(1-methylimidazolium)-methylpropane-1,3-diol bromide),1,2-bis(2′-hydroxyethyl)imidazolium bromide,(3-hydroxy-2-(hydroxymethyl)-2-methylpropyl)-3-methyl-1H-3λ⁴-imidazol-1-iumbromide, 2,2-bis(hydroxymethyl)butyric acid,N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid,N-methyl-2,2′-iminodiethanol, 3-dimethylamino-1,2-propanediol,2,2-bis(hydroxymethyl)propionic acid, 1,4-bis(2-hydroxyethyl)piperazine,2,6-diaminocaproic acid, N,N-bis(2-hydroxyethyl)glycine,2-hydroxypropanoic acid hemicalsium salt, dimethylolpropionic acid,N-methyldiethanolamine, N-ethyldiethanolamine, N-propyldiethanolamine,N-benzyldiethanolamine, N-t-butyldiethanolamine, bis(2-hydroxyethyl)benzylamine, bis(2-hydroxypropyl) aniline, and homologues, combinations,derivatives, or reaction products thereof.

Within the segmented copolymer, the isocyanate species may be selectedfrom the group consisting of 4,4′-methylenebis(cyclohexyl isocyanate),hexamethylene diisocyanate, cycloalkyl-based diisocyanates,tolylene-2,4-diisocyanate, 4,4′-methylenebis(phenyl isocyanate),isophorone diisocyanate, and combinations or derivatives thereof.

The polyol or polyamine chain extenders or crosslinkers may have anaverage functionality of at least 3. In some embodiments, the polyol orpolyamine chain extenders or crosslinkers are selected from the groupconsisting of 1,3-butanediol, 1,4-butanediol, 1,3-propanediol,1,2-ethanediol, diethylene glycol, triethylene glycol, tetraethyleneglycol, propylene glycol, dipropylene glycol, tripropylene glycol,neopentyl glycol, 1,6-hexane diol, 1,4-cyclohexanedimethanol, ethanolamine, diethanol amine, methyldiethanolamine, phenyldiethanolamine,glycerol, trimethylolpropane, 1,2,6-hexanetriol, triethanolamine,pentaerythritol, ethylenediamine, 1,3-propanediamine, 1,4-buatendiamine,diethyltoluenediamine, dimethylthiotoluenediamine, isophoronediamine,diaminocyclohexane, N,N,N′,N′-tetrakis (2-hydroxypropyl)ethylenediamine, and homologues, combinations, derivatives, or reactionproducts thereof.

As intended herein, “light” means the ultraviolet and/or visible regionsof electromagnetic radiation, with wavelengths of about 10 nm to about1000 nm, such as about 100 nm to about 700 nm.

Some preferred embodiments utilize sunlight, which is a clean, abundantenergy source. Sunlight (solar light) is therefore a convenient,low-cost source of visible light to induce chemical and physical changesin polymer compositions disclosed herein. As is known, solar light isnot monochromatic. The sun emits light primarily in the visible spectrum(about 400-700 nm), but it also emits photons at other wavelengths,starting at about 200 nm and exceeding 2000 nm.

An alternative to sunlight is artificial light, from a laser source,ambient source (other than the sun), or other source. The light may betransmitted through space or through a material such as an opticalfiber, for exposure to the polymer. In some embodiments, a light sourceis spatially dividing into one or more individual beams, focusing on aselected region of the polymer (e.g., for directed healing of cracks).Certain embodiments utilize laser-guided healing of selected locationsin a polymer system.

In some embodiments, the light exposure is temporary, to cause aproperty change. The light exposure may be periodic, i.e. with somedefined interval between light treatments, or non-periodic (e.g.,on-demand). Constant light exposure may be utilized, to maintainthermoplastic properties even in the presence of random oxidants whichwould otherwise tend to reverse the polymer to thermoset properties, forexample.

Other variations of the invention provide a polymer compositioncomprising:

(a) a polymer matrix containing one or more ionic species;

(b) one or more chemical reducing agents capable of causing metalreduction; and

(c) one or more metal ions capable of reversibly changing valence from afirst oxidation state to a second oxidation state when in the presenceof the chemical reducing agents,

wherein the metal ions, in the first oxidation state, have a firstcoordination number with the ionic species,

wherein the metal ions, in the second oxidation state, have a secondcoordination number with the ionic species, and

wherein the first coordination number is greater than the secondcoordination number.

A “reducing agent” (also called a “reductant” or “reducer”) is anelement or compound that donates an electron to another chemical speciesin a redox chemical reaction. A wide variety of chemical reducing agentsmay be employed. Some examples are organic acids (e.g., ascorbic acid)and catechols (e.g., 1,2-dihydroxybenzene).

In some embodiments, the reducing agent requires light for activation,while in other embodiments, the reducing agent does not require lightfor activation. Certain reducing agents will work without light but willbe more effective (e.g., faster reduction of metal ions) with at leastsome light present.

Variations of the invention provide a reversibly crosslinkable polymercomposition comprising:

(a) a polymer matrix containing one or more ionic species; and

(b) one or more metal ions characterized in that the metal ions (i)change valence from a first oxidation state to a second oxidation statewhen in the presence of a reducing agent, and (ii) change valence fromthe second oxidation state back to the first oxidation state when in thepresence of an oxidizing agent,

wherein the metal ions, in the first oxidation state, have a firstcoordination number with the ionic species,

wherein the metal ions, in the second oxidation state, have a secondcoordination number with the ionic species,

wherein the first coordination number is greater than the secondcoordination number, and

wherein the polymer composition has a higher crosslink density at thefirst coordination number than at the second coordination number.

The reducing agent (e.g., a photosensitizer) is typically present in thepolymer composition itself, while the oxidizing agent (e.g., oxygen) istypically not present in the polymer composition. However, it ispossible to use an external reducing agent, such as hydrogen, carbonmonoxide, or syngas (mixture of hydrogen and carbon monoxide). It isalso possible to incorporate an oxidizing agent in the polymercomposition. The oxidizing agent may be responsive to an externalactivating signal which could be magnetic or electromagnetic but in adifferent spectrum than visible or UV light, for example.

The reversible crosslink density can give rise to many reversibledifferences in properties, including chemical properties (e.g., solventor acid resistance), physical properties (e.g. density or porosity),mechanical properties (e.g., strength or toughness), electricalproperties (e.g., electrical resistivity), and so on.

In some embodiments, the polymer composition is characterized as“thermoplastic/thermoset—switchable” which means that the compositioncan be transformed between thermoset properties at the metal ion firstcoordination number, on the one hand, and thermoplastic properties atthe metal ion second coordination number, on the other hand. The secondcoordination number is lower than the first coordination number whichcauses a lower crosslink density and, therefore, mechanical propertiesassociated with thermoplastic polymers. This can be done for a certainperiod of time, such as to allow the polymer to self-heal (e.g., repaircracks or other defects)—followed by reversal back to the thermosetproperties arising from the higher crosslink density (first coordinationnumber).

In preferred embodiments, the reversible crosslinking of the polymernetwork does not utilize high temperature (heating) as a trigger. Invarious embodiments, reversible crosslinking occurs in response to anacid, a base, and/or light-mediated chemical reduction of metal ions. Inpreferred embodiments, the polymer network is contained in a film orcoating, not in a sol-gel system.

Some embodiments utilize the disclosure in Oster et al., “Photoreductionof metal ions by visible light,” 135th National meeting of the AmericanChemical Society, Apr. 9, 1959, which is hereby incorporated byreference herein for its teaching of the reduction of various metal ionswith a photoreducing dye in the presence of a sacrificial anion undervisible light. This technique may be used to reduce metal ions embeddedwithin polymer films and coatings disclosed herein.

As used herein, an “ionic species” refers to ionized or ionizablemolecules which may be in the form of, or precursors to, anions,cations, or zwitterions. Ionic species may include (or be ionizable to)a full charge such as −1, −2, −3, +1, +2, +3, a fractional charge suchas −0.5, +0.5, −1.5 or +1.5, or a partial charge which in principle maybe any fraction of charge. “Ionizable” means that the molecule isneutral, i.e. net charge of 0, but capable of forming an anion, cation,or zwitterion; or that it is ionized but is capable of forming an anion,cation, or zwitterion having a larger magnitude of charge.

In some embodiments, the ionic species are high-molecular-weightpolyelectrolytes or polyelectrolyte precursors. A “polyelectrolyte” isdefined as a macromolecule in which a substantial portion of theconstitutional units have ionizable or ionic groups, or both.

Some embodiments incorporate small-molecule charged groups (e.g.,polymer pendant groups) along the chain backbone at various locations,depending on the order of addition. In these embodiments, the electricalcharge is typically present within the pendant group, not in the polymerbackbone itself.

In some embodiments, the ionic species are classified as ionomers. An“ionomer” is a polymer composed of ionomer molecules. An “ionomermolecule” is a macromolecule in which a significant (e.g., greater than1, 2, 5, 10, 15, 20, or 25 mol %) proportion of the constitutional unitshave ionizable or ionic groups, or both. Some embodiments employurethane-based ionomers capable of changing their crosslinked stateunder the influence of a change in counterion valance.

A zwitterion is a neutral molecule with a positive as well as a negativeelectrical charge. Multiple positive and negative charges may bepresent. Zwitterions are sometimes also called inner salts. Unlikesimple amphoteric compounds that might only form either a cationic oranionic species depending on external conditions, a zwitterionsimultaneously has both ionic states in the same molecule.

In addition to one or more ionic species, various counterions may bepresent, either intentionally (e.g., metal ions) or arising fromexternal conditions. A counterion may or may not be present; that is,there may be a net charge associated with the ionic species, or theremay be charge neutrality if a sufficient amount of counterions, such asmetal ions, are ionically associated with the ionic species. It ispossible for there to be partial neutralization due to counterions, sothat the effective charge is something between the ionic species chargeand 0. It is also possible for there to be, at least for some period oftime, an excess of counterions so that the effective charge is greaterthan the ionic species charge (i.e. more positive or more negative whenthe ionic species is cationic or anionic, respectively).

Ionic constituents in polymers are both water-absorbing and typicallybound with counterions. When incorporated into polymer systems, ionicspecies have the ability to change the bulk and surface properties inresponse to materials bound to the network. These charged constituents,when incorporated into the polymer coating, can enable reversibleinterchain crosslinking in some embodiments. Upon addition into thepolymer, the functional groups may be protonated and uncharged, allowingthe network to be held together by the hydrogen bonding in hard-segmentdomains of concentrated urethane bonds.

For example, to crosslink polymer films with metal ions, films may besoaked in metal-containing solutions, such as calcium hydroxide(Ca(OH)₂) solutions. Calcium ions are known to bind very tightly tocarboxylic acid groups where their divalent nature can act as a bridgebetween two monovalent carboxylate species to crosslink chains into anoverall network. The material may subsequently be soaked in an acidicsolution, such as hydrochloric acid solutions, to protonate thecarboxylic acid groups for removal of Ca²⁺ ions, in reversiblecrosslinking.

As mentioned above, an ionomer is a polymer that comprises repeat unitsof both electrically neutral repeating units and a fraction of ionizedunits (such as about 1-15 mol %) covalently bonded to the polymerbackbone as pendant group moieties. This means that ionomers arecommonly copolymers of the neutral segments and the ionized units, whichmay consist of (as an example) carboxylic acid groups.

Ionomer synthesis may include the introduction of acid groups to thepolymer backbone and the neutralization of some of the acid groups by ametal cation. In some embodiments, the groups introduced are alreadyneutralized by a metal cation. The introduction of acid groups may beachieved by copolymerizing a neutral non-ionic monomer with a monomerthat contains pendant acid groups. Alternatively, acid groups may beadded to a non-ionic polymer through post-reaction modifications. Insome embodiments, the acid form of the copolymer is synthesized (i.e.all of the acid groups are neutralized by hydrogen cations) and theionomer is formed through subsequent neutralization by a metal cation.An acid copolymer may be melt-mixed with a basic metal, orneutralization may be achieved through solution processes, for example.The identity of the neutralizing metal cation has an effect on thephysical properties of the ionomer.

The classification of a polymer as an ionomer versus polyelectrolyte(see below) depends on the level of substitution of ionic groups as wellas how the ionic groups are incorporated into the polymer structure. Forexample, polyelectrolytes also have ionic groups covalently bonded tothe polymer backbone, but have a higher ionic group molar substitutionlevel (such as greater than 50 mol %, usually greater than 80 mol %).

Polyelectrolytes (charged molecular chains) are polymers whose repeatingunits bear an electrolyte group. Polycations and polyanions arepolyelectrolytes. These groups dissociate in aqueous solutions, makingthe polymers charged. Polyelectrolyte properties are thus similar toboth electrolytes (salts) and polymers and are sometimes calledpolysalts. Like salts, their solutions are electrically conductive. Likepolymers, their solutions are often viscous.

Polyelectrolytes can be divided into weak and strong types. A strongpolyelectrolyte is one which dissociates completely in solution for mostreasonable pH values. A weak polyelectrolyte, by contrast, has adissociation constant in the range of about 2 to 10, meaning that itwill be partially dissociated at intermediate pH. Thus, weakpolyelectrolytes are not fully charged in solution, and their fractionalcharge can be modified by changing the solution pH, counterionconcentration, or ionic strength.

A polyacid is a polyelectrolyte composed of macromolecules containingacid groups on a substantial fraction of the constitutional units. Forexample, the acid groups may be —COOH, —SO₃H, or —PO₃H₂.Polyelectrolytes which bear both cationic and anionic repeat groups arecalled polyampholytes.

In some embodiments of the invention, the ionic species include two ormore reactive groups such as alcohol or amine moieties. Specific exampleinclude, but are not limited to, 2,2-bis(hydroxymethyl)butyric acid,N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid,N-methyl-2,2′-iminodiethanol, 3-dimethylamino-1,2-propanediol,2,2-bis(hydroxymethyl)propionic acid, 1,4-bis(2-hydroxyethyl)piperazine,2,6-diaminocaproic acid, N,N-bis(2-hydroxyethyl)glycine,2-hydroxypropanoic acid hemicalcium salt, 2,2-bis-(1-(1-methylimidazolium)-methylpropane-1,3-diol bromide),1,2-bis-(2′-hydroxyethyl)imidazolium bromide,(3-hydroxy-2-(hydroxymethyl)-2-methylpropyl)-3-methyl-1H-3λ⁴-imidazol-1-iumbromide, dimethylolpropionic acid, N-methyldiethanolamine,N-ethyldiethanolamine, N-propyldiethanolamine, N-benzyldiethanolamine,N-t-butyldiethanolamine, bis(2-hydroxyethyl) benzylamine, andbis(2-hydroxypropyl) aniline.

Partial atomic charges can be used to quantify the degree of ionicversus covalent bonding of any particular compound that is selected as,or may be a candidate for, an ionic species. Partial charges for a givenionic species can be estimated in multiple ways, such as: densities;measured dipole moments; the Extended Born thermodynamic cycle,including an analysis of ionic bonding contributions; the influence ofcoordination numbers and aggregate state of a given compound on atomiccharges; the relationship of atomic charges to melting points,solubility, and cleavage energies for a set of similar compounds withsimilar degree of covalent bonding; the relationship of atomic chargesto chemical reactivity and reaction mechanisms for similar compounds; orthe relationship between chemical structure and atomic charges forcomparable compounds with known atomic charges.

Partial charges in ionic species may be determined by populationanalysis of wavefunctions (e.g., Mulliken population analysis, Coulson'scharges, etc.); partitioning of electron density distributions (e.g.,Bader charges, Hirshfeld charges, Politzer's charges, etc.); chargesderived from dipole-dependent properties (e.g., dipole charges, dipolederivative charges, Born, Callen, or Szigeti effective charges, etc.);charges derived from electrostatic potential (e.g., Chelp,Merz-Singh-Kollman, etc.); charges derived from spectroscopic data(e.g., charges from infrared intensities, X-ray photoelectronspectroscopy, X-ray emission spectroscopy, X-ray absorption spectra,UV-vis intensities of transition metal complexes, etc.); charges fromother experimental data (e.g., charges from bandgaps or dielectricconstants, apparent charges from the piezoelectric effect, chargesderived from adiabatic potential energy curves, orelectronegativity-based charges), or formal charges.

In a specific embodiment, a segmented copolymer composition is employed.The composition comprises one or more α,ω (alpha,omega)-amine-terminated or α,ω (alpha, omega)-hydroxyl-terminatedpolyfluoropolymer first soft segments having an average molecular weightof between about 500 grams per mole to about 20,000 grams per mole. Theexemplary composition further comprises one or more polyethylene glycolsecond soft segments having an average molecular weight of between about500 grams per mole to about 20,000 grams per mole. Additionally, thecomposition may comprise one or more low-molecular-weight chargedmonomer species. A total content of the one or more first soft segmentsand the one or more second soft segments is from about 40% by weight toabout 90% by weight, based on a total weight percent of the composition.The composition further comprises one or more hard segments present, forexample, in an amount of from about 15% by weight to about 50% byweight, based on the total weight percent of the composition. The one ormore hard segments comprise a combination of one or more isocyanatespecies and one or more low-molecular-weight polyol or polyamine chainextenders or crosslinkers.

Some variations utilize a segmented copolymer composition comprising:

(a) one or more first soft segments selected from fluoropolymers havingan average molecular weight from about 500 g/mol to about 20,000 g/mol,wherein the fluoropolymers are (α,ω)-hydroxyl-terminated and/or(α,ω)-amine-terminated;

(b) optionally, one or more second soft segments selected frompolyesters or polyethers, wherein the polyesters or polyethers are(α,ω)-hydroxyl-terminated and/or (α,ω)-amine-terminated;

(c) one or more ionic species contained within the soft segments and/orcontained in copolymer chains that are distinct from the soft segments;

(d) one or more isocyanate species, or a reacted form thereof,possessing an isocyanate functionality of 2 or greater; and

(e) one or more polyol or polyamine chain extenders or crosslinkers, ora reacted form thereof.

It is noted that (α,ω)-terminated polymers are terminated at each end ofthe polymer. The α-termination may be the same or different than theω-termination. Also it is noted that in this disclosure,“(α,ω)-termination” includes branching at the ends, so that the numberof terminations may be greater than 2 per polymer molecule. The polymersherein may be linear or branched, and there may be various terminationsand functional groups within the polymer chain, besides the end (α,ω)terminations.

In some embodiments, the molar ratio of the second soft segments (whenpresent) to the first soft segments is from about 0.1 to about 2.0. Invarious embodiments, the molar ratio of the second soft segments to thefirst soft segments is about 0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7,0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 1.95.

In this description, “polyurethane” is a polymer comprising a chain oforganic units joined by carbamate (urethane) links, where “urethane”refers to N(H)—(C═O)—O—. Polyurethanes are generally produced byreacting an isocyanate containing two or more isocyanate groups permolecule with one or more polyols containing on average two or morehydroxyl groups per molecule, in the presence of a catalyst.

Polyols are polymers in their own right and have on average two or morehydroxyl groups per molecule. For example, α,ω-hydroxyl-terminatedperfluoropolyether is a type of polyol.

“Isocyanate” is the functional group with the formula —N═C═O. For thepurposes of this disclosure, S—C(═O)—N(H)—R is considered a derivativeof isocyanate.

“Polyfluoroether” refers to a class of polymers that contain an ethergroup—an oxygen atom connected to two alkyl or aryl groups, where atleast one hydrogen atom is replaced by a fluorine atom in an alkyl oraryl group.

“Perfluoropolyether” (PFPE) is a highly fluorinated subset ofpolyfluoroethers, wherein all hydrogen atoms are replaced by fluorineatoms in the alkyl or aryl groups.

“Polyurea” is a polymer comprising a chain of organic units joined byurea links, where “urea” refers to N(H)—(C═O)—N(H)—. Polyureas aregenerally produced by reacting an isocyanate containing two or moreisocyanate groups per molecule with one or more multifunctional amines(e.g., diamines) containing on average two or more amine groups permolecule, in the presence of a catalyst.

A “chain extender or crosslinker” is a compound (or mixture ofcompounds) that link long molecules together and thereby complete apolymer reaction. Chain extenders or crosslinkers are also known ascuring agents, curatives, or hardeners. In polyurethane/urea systems, acurative is typically comprised of hydroxyl-terminated oramine-terminated compounds which react with isocyanate groups present inthe mixture. Diols as curatives form urethane linkages, while diaminesas curatives form urea linkages. The choice of chain extender orcrosslinker may be determined by end groups present on a givenprepolymer. In the case of isocyanate end groups, curing can beaccomplished through chain extension using multifunctional amines oralcohols, for example. Chain extenders or crosslinkers can have anaverage functionality greater than 2, such as 3 or greater, i.e. beyonddiols or diamines.

The one or more chain extenders or crosslinkers (or reaction productsthereof) may be present in a concentration, in the segmented copolymercomposition, from about 0.01 wt % to about 10 wt %, such as about 0.05wt % to about 1 wt %.

As meant herein, a “low-surface-energy polymer” means a polymer, or apolymer-containing material, with a surface energy of no greater than 50mJ/m². The principles of the invention may be applied tolow-surface-energy materials with a surface energy of no greater than 50mJ/m², in general (i.e., not necessarily limited to polymers).

In some embodiments, the low-surface-energy polymer includes afluoropolymer, such as (but not limited to) a fluoropolymer selectedfrom the group consisting of polyfluoroethers, perfluoropolyethers,fluoroacrylates, fluorosilicones, and combinations thereof.

In these or other embodiments, the low-surface-energy polymer includes asiloxane. A siloxane contains at least one Si—O—Si linkage. Thelow-surface-energy polymer may consist of polymerized siloxanes orpolysiloxanes (also known as silicones). One example ispolydimethylsiloxane.

In some embodiments, the fluoropolymers are selected from the groupconsisting of perfluoropolyethers, polyfluoroacrylates,polyfluorosiloxanes, and combinations thereof. In certain embodiments,the fluoropolymers include a fluoropolymer copolymer with poly(ethyleneglycol) having the formulaHO—(CH₂—CH₂—O)_(p)—CH₂—CF₂—O—(CF₂—CF₂—O)_(m)(CF₂—O)_(n)—CF₂—CH₂—(O—CH₂—CH₂)_(p)—OH(p=0 to 50; m=1 to 100; and n=1 to 100), with the following structure:

wherein:

-   X=CH₂—(O—CH₂—CH₂)_(p)—OH wherein p=0 to 50;-   m=1 to 100; and-   n=1 to 100.

In certain embodiments, the chain ends include different PEG chainlengths. That is, the fluoropolymers may include a fluoropolymersegmented copolymer with poly(ethylene glycol) having the formulaHO—(CH₂—CH₂—O)_(p)—CH₂—CF₂—O—(CF₂—CF₂—O)_(m)(CF₂—O)_(n)—CF₂—CH₂—(O—CH₂—CH₂)_(q)—OHwherein p=0 to 50; q=0 to 50 and q is independently selected from p; m=1to 100; and n=1 to 100. In certain of these embodiments, one of either por q is selected from 6 to 50 while the other is selected from 0 to 50.In some embodiments, one or both of the X groups is amine-terminatedrather than hydroxyl-terminated.

In some embodiments, the polyesters or polyethers are selected from thegroup consisting of poly(oxymethylene), poly(ethylene glycol),poly(propylene glycol), poly(tetrahydrofuran), poly(glycolic acid),poly(caprolactone), poly(ethylene adipate), poly(hydroxybutyrate),poly(hydroxyalkanoate), and combinations thereof.

In some embodiments, the isocyanate species is selected from the groupconsisting of 4,4′-methylenebis(cyclohexyl isocyanate), hexamethylenediisocyanate, cycloalkyl-based diisocyanates, tolylene-2,4-diisocyanate,4,4′-methylenebis(phenyl isocyanate), isophorone diisocyanate, andcombinations or derivatives thereof.

The polyol or polyamine chain extender possesses a functionality of 2 orgreater, in some embodiments. At least one polyol or polyamine chainextender may be selected from the group consisting of 1,4-butanediol,1,3-propanediol, 1,2-ethanediol, glycerol, trimethylolpropane,ethylenediamine, isophoronediamine, diaminocyclohexane, and homologues,derivatives, or combinations thereof.

Following a suitable chemical reaction, the segmented copolymercomposition contains, in a hard segment, the reacted form of the one ormore isocyanate species, combined with the reacted form of the one ormore polyol or polyamine chain extenders or crosslinkers. In someembodiments, the hard segment is present in an amount from about 5 wt %to about 60 wt %, based on total weight of the composition.

The segmented copolymer composition may be present in a film or coating,for example. Such a coating may be characterized by a contact angle ofwater on a coating surface of greater than 90°. Such a coating may becharacterized by an average kinetic delay of surface ice formation of atleast 5 minutes at −10° C.

The structure of some variations of the invention is shown in FIG. 1.FIG. 1 depicts the structure of a coating or surface with anti-foulingproperties.

The structure 100 of FIG. 1 includes a continuous matrix 110. A“continuous matrix” (or equivalently, “substantially continuous matrix”)means that the matrix material is present in a form that includeschemical bonds among molecules of the matrix material. An example ofsuch chemical bonds is crosslinking bonds between polymer chains. Thestructure 100 further includes a plurality of inclusions 120, dispersedwithin the matrix 110, each of the inclusions 120 comprising ahygroscopic material containing one or more ionic species. In certainembodiments, the hygroscopic material is fabricated from ionomers,polyelectrolytes, and/or other ionic species described above. At leastone of the matrix 110 or inclusions 120 preferably contains aphotosensitizer, a chemical reducing agent, or a combination thereof,along with one or more metal ions capable of reversibly changing from afirst oxidation state to a second oxidation state. Note that thefunctions of the matrix and inclusions may be reversed, such that thematrix provides hygroscopic properties while the inclusions provide lowsurface energy. In some embodiments, both the matrix 110 and inclusions120 contains a photosensitizer, a chemical reducing agent, or acombination thereof, along with one or more metal ions capable ofreversibly changing from a first oxidation state to a second oxidationstate.

Optionally, the continuous matrix 110 may further comprise one or moreadditives selected from the group consisting of fillers, colorants, UVabsorbers, defoamers, plasticizers, viscosity modifiers, densitymodifiers, catalysts, and scavengers. In a substantially continuousmatrix 110, there may be present various defects, cracks, broken bonds,impurities, additives, and so on.

FIG. 2 shows a schematic of the reduction of metal ions, indicated forillustration as being reduced from a +2 charge to a +1 charge. Chargedfunctional groups, with a negative charge, bind to the metal ions. Thecharged functional groups are present in a polymer network and arecapable of binding to the metal ions. As the metal charge increasesbeyond +1, multiple functional groups can bind to a single ion, actingas crosslinks for the polymer network. Ionic crosslinking with metalspecies of valence charges >1 has been demonstrated experimentally (seeExample G), with changes in mechanical properties after reducing themetal species chemically or with light.

Some variations provide an anti-fouling material (e.g., coating or bulkmaterial) comprising:

a substantially continuous matrix containing a first component;

a plurality of inclusions containing a second component, wherein theinclusions are dispersed within the matrix;

one or more metal ions characterized in that the metal ions (i) changevalence from a first oxidation state to a second oxidation state when inthe presence of a reducing agent, and (ii) change valence from thesecond oxidation state back to the first oxidation state when in thepresence of an oxidizing agent,

wherein one of the first component or the second component is alow-surface-energy polymer having a surface energy between about 5 mJ/m²to about 50 mJ/m², and the other of the first component or the secondcomponent is a hygroscopic material containing one or more ionicspecies,

wherein the low-surface-energy polymer and the hygroscopic material arechemically connected ionically or covalently,

wherein the continuous matrix and the inclusions form a lubricatingsurface layer in the presence of humidity,

wherein the metal ions, in the first oxidation state, have a firstcoordination number with the ionic species,

wherein the metal ions, in the second oxidation state, have a secondcoordination number with the ionic species, and

wherein the first coordination number is greater than the secondcoordination number.

In some embodiments, the surface energy of the low-surface-energypolymer is between about 10 mJ/m² to about 40 mJ/m², such as about 10,15, 20, 25, 30, 35, or 40, mJ/m². In some preferred embodiments, thelow-surface-energy polymer is a fluoropolymer selected from the groupconsisting of polyfluoroethers, perfluoropolyethers,polyfluoroacrylates, polyfluorosiloxanes, and combinations thereof.

The hygroscopic material may include a material selected from the groupconsisting of 2,2-bis-(1-(1-methyl imidazolium)-methylpropane-1,3-diolbromide), 1,2-bis(2′-hydroxyethyl)imidazolium bromide,(3-hydroxy-2-(hydroxymethyl)-2-methylpropyl)-3-methyl-1H-3λ⁴-imidazol-1-iumbromide, 2,2-bis(hydroxymethyl) butyric acid,N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid,N-methyl-2,2′-iminodiethanol, 3-dimethylamino-1,2-propanediol,2,2-bis(hydroxymethyl)propionic acid, 1,4-bis(2-hydroxyethyl)piperazine,2,6-diaminocaproic acid, N,N-bis(2-hydroxyethyl)glycine,2-hydroxypropanoic acid hemicalsium salt, dimethylolpropionic acid,N-methyldiethanolamine, N-ethyldiethanolamine, N-propyldiethanolamine,N-benzyldiethanolamine, N-t-butyldiethanolamine, bis(2-hydroxyethyl)benzylamine, bis(2-hydroxypropyl) aniline, and homologues, combinations,derivatives, or reaction products thereof.

The hygroscopic material may include a material selected from the groupconsisting of poly(acrylic acid), poly(ethylene glycol),poly(2-hydroxyethyl methacrylate), poly(vinyl imidazole),poly(2-methyl-2-oxazoline), poly(2-ethyl-2-oxazoline),poly(vinylpyrolidone), cellulose, modified cellulose, carboxymethylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methylcellulose, hydrogels, PEG diacryalate, monoacrylate, and combinationsthereof. When the hygroscopic material includes one or more of thematerials from this list, the hygroscopic material may further includeone or more ionic species selected from the group consisting of2,2-bis-(1-(1-methyl imidazolium)-methylpropane-1,3-diol bromide),1,2-bis(2′-hydroxyethyl)imidazolium bromide,(3-hydroxy-2-(hydroxymethyl)-2-methylpropyl)-3-methyl-1H-3λ⁴-imidazol-1-iumbromide, 2,2-bis(hydroxymethyl)butyric acid,N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid,N-methyl-2,2′-iminodiethanol, 3-dimethylamino-1,2-propanediol,2,2-bis(hydroxymethyl)propionic acid, 1,4-bis(2-hydroxyethyl)piperazine,2,6-diaminocaproic acid, N,N-bis(2-hydroxyethyl)glycine,2-hydroxypropanoic acid hemicalsium salt, dimethylolpropionic acid,N-methyldiethanolamine, N-ethyldiethanolamine, N-propyldiethanolamine,N-benzyldiethanolamine, N-t-butyldiethanolamine, bis(2-hydroxyethyl)benzylamine, bis(2-hydroxypropyl) aniline, and homologues, combinations,derivatives, or reaction products thereof.

The low-surface-energy polymer and the hygroscopic material may bephase-separated, i.e. they do not form a single continuous phase. Thereis preferably chemical and/or physical bonding between thelow-surface-energy polymer and the hygroscopic material.

In some embodiments, the inclusions are three-dimensional objects ordomains, which may be of any shape, geometry, or aspect ratio. In athree-dimensional object, an aspect ratio of exactly 1.0 means that allthree characteristic length scales are identical, such as in a perfectcube. The aspect ratio of a perfect sphere is also 1.0. The inclusionsmay be geometrically symmetric or asymmetric. Randomly shaped asymmetrictemplates are, generally speaking, geometrically asymmetric. In someembodiments, inclusions are geometrically symmetric. Examples includecylinders, cones, rectangular prisms, pyramids, or three-dimensionalstars.

In some embodiments, the inclusions are anisotropic. As meant herein,“anisotropic” inclusions have at least one chemical or physical propertythat is directionally dependent. When measured along different axes, ananisotropic inclusion will have some variation in a measurable property.The property may be physical (e.g., geometrical) or chemical in nature,or both.

The inclusions may be characterized as templates, domains, or regions(such as phase-separated regions). In some embodiments, the inclusionsare not a single, continuous framework in the coating. Rather, theinclusions are discrete, non-continuous and dispersed in the continuousmatrix. The hygroscopic inclusions may be dispersed uniformly within thecontinuous matrix. In some anti-fouling materials, thelow-surface-energy polymer and the hygroscopic material are covalentlyconnected in a block copolymer, in which the inclusions and thecontinuous matrix are distinct phases of the block copolymer.

As intended herein, a “block copolymer” means a copolymer containing alinear arrangement of blocks, where each block is defined as a portionof a polymer molecule in which the monomeric units have at least oneconstitutional or configurational feature absent from the adjacentportions. Several types of block copolymers are generally possible,including AB block copolymers, ABA block copolymers, ABC blockcopolymers, segmented block copolymers, and random copolymers. Segmentedblock copolymers are preferred, in some embodiments of the invention.

A wide range of concentrations of components may be present in theanti-fouling material. For example, the continuous matrix may be fromabout 5 wt % to about 95 wt %, such as from about 10 wt % to about 50 wt% of the material. The inclusions may be from about 1 wt % to about 90wt %, such as from about 10 wt % to about 50 wt % of the coating.

Within the component containing the low-surface-energy polymer, thelow-surface-energy polymer may be from about 50 wt % to 100 wt %, suchas about 60, 70, 80, 90, 95, or 100 wt %. Within the componentcontaining the hygroscopic material, the hygroscopic material may befrom about 50 wt % to 100 wt %, such as about 60, 70, 80, 90, 95, or 100wt %.

The low-surface-energy polymer and/or the hygroscopic material may besurface-treated, such as to adjust hydrophobicity. The anti-foulingmaterial optionally further contains one or more additional componentsselected from the group consisting of a particulate filler, a pigment, adye, a plasticizer, a flame retardant, a flattening agent, and asubstrate adhesion promoter.

A particulate filler may be selected from the group consisting ofsilica, alumina, silicates, talc, aluminosilicates, barium sulfate,mica, diatomite, calcium carbonate, calcium sulfate, carbon,wollastonite, and combinations thereof. The particulate fillersgenerally should be in the size range of about 5 nm to about 2 μm, suchas about 20 nm to 100 nm.

The particulate fillers may be surface-modified with a compound selectedfrom the group consisting of fatty acids, silanes, silicones, alkylphosphonates, alkyl phosphonic acids, alkyl carboxylates, andcombinations thereof. Optionally, the fillers may be surface-modifiedwith a hydrophobic material, such as (but not limited to) analkylsilane, a fluoroalkylsilane, and/or an alkyldisilazane (e.g.,hexamethyldisilazane).

In some embodiments, the material further includes voids. As intendedherein, a “void” is a discrete region of empty space, or space filledwith air or another gas, that is enclosed within the continuous matrix.The voids may be open (e.g., interconnected voids) or closed (isolatedwithin the continuous matrix), or a combination thereof. The voids maypartially surround inclusions.

The domains of hygroscopic material exist throughout the material, inboth planar and depth dimensions. The anti-fouling function is retainedeven after some sort of abrasion of the top layer of the material.

Some compositions include both a polyether and an aliphatic diolcarrying an acid group as part of the composition, but does not includealiphatic diols containing long carbon chains having >10 carbons. Someembodiments do not incorporate polyols containing three or more reactivehydroxyl groups. Some compositions contain ionizable groups incombination with perfluoropolyethers, but do not incorporate silanes forcrosslinking. Preferred embodiments do not incorporate waterbornepolyurethanes with charged groups to create stable colloidal dispersionsin water. Other preferred embodiments do not use ionic liquidcounterions.

Some variations are premised on the incorporation of a material thatpossesses both low surface energy (for low adhesion) and the ability toabsorb water. A structured material or coating, as disclosed, passivelyabsorbs water from the atmosphere, to create a lubrication/self-cleaninglayer and reduce the friction and adhesion of the impacting body (suchas an insect) on the surface. This anti-fouling material may be used asa coating or as a surface, for example.

Certain embodiments combine a fluorinated perfluoropolyether (PFPE) as alow-surface-energy component and polyethylene glycol (PEG) as awater-absorbing species in a urethane-based segmented copolymer.Preferred embodiments incorporate ionic species into or onto the polymerchain backbone to increase the water-absorbing power (hygroscopicbehavior) of the overall structure, beyond that of the PEG speciesalone. Improvement in lubrication or decrease in the coefficient offriction better enables material to be cleared from a surface using thenatural motion of an automotive or aerospace vehicle, for example. Insome embodiments, the presence of ionic species in the coating increasesthe amount of water naturally absorbed from the atmosphere and thusincreases the lubrication, i.e. decreases the coefficient of friction atthe surface.

An anti-fouling coating in some embodiments may be characterized as“bugphobic,” which is intended to mean the coating has relatively lowadhesion with an impacting bug. Materials in some embodiments can trap alayer of water near the surface, thereby delaying the formation of ice.An anti-fouling coating in some embodiments may be characterized as“icephobic,” which is intended to mean the coating is capable ofdelaying the formation of ice and/or causing a freezing-point depressionof ice, compared to a bare substrate. The lubricating component has theability to trap and organize a layer of water at the surface to inhibitfreezing.

The disclosed material, in some embodiments, can absorb water from theair and use this water as a lubricant to wash and remove debris from thesurface. The surface may contain domains of a low-surface-energy polymer(such as, but not limited to, a fluoropolymer) providing low adhesion,and domains of a hygroscopic material. The atmospheric water is thuscaptured as a lubricant and is a continually available, renewableresource.

By reducing friction, the debris is less likely to embed in or otherwiseattach to the surface and instead will tend to slough off the surface,particularly under the shear forces from air moving over a vehiclesurface. Debris may be organic or inorganic and may include insects,dirt, dust, soot, ash, pollutants, particulates, ice, seeds, plant oranimal fragments, plant or animal waste products, combinations orderivatives of any of the foregoing, and so on.

In some variations, anti-fouling structures are created by aheterogeneous microstructure comprising a low-surface-energy polymerthat is interspersed with hygroscopic domains (lubricating inclusions).Debris impacting the surface has low adhesion energy with the surface,due to the presence of the low-surface-energy polymer, and the debriswill not tend to remain on the surface.

Some embodiments employ fluoropolymers, without limitation of theinvention, as described in more detail below. A preferred technique tocompatibilize fluoropolymers and hygroscopic materials is the use ofsegmented polyurethane or urea systems. These species demonstrate stronghydrogen bonding potential between them and as a result can createstrong associative forces between the chains. In order to produceelastomeric materials, regions of highly flexible and weakly interactingchains (soft segments) must be incorporated with strongly associatingelements (hard segments) and this can be provided in a segmentedcopolymerization scheme. Segmented copolymers provide a straightforwardsynthetic route toward block architectures using segments with vastlydiffering properties. Such synthesis results in chains that possessalternating hard and soft segments composed of regions of high urethanebond density and the chosen soft segment component (e.g., fluoropolymeror hygroscopic element), respectively. This covalent linkage ofdissimilar hard and soft blocks drives the systems to microphaseseparation and creates regions of flexible soft blocks surroundingregions of hard blocks. The associative forces among the hard segmentsprevent flow under stress and can produce elastomeric materials capableof displaying high elongation and tensile strength.

It has been discovered that the hygroscopic or water-absorbing characterof the overall polymer film can be enhanced by the addition of ionicspecies as a hygroscopic soft segment component to complement thefluorinated soft segment, and/or as a separate soft segment inconjunction with other soft segments present. Due to their highly polarnature, ionic species have the ability to efficiently absorb watereither when submerged in aqueous solution or naturally from the air invapor form.

The coefficient of friction of the anti-fouling material, according tosome embodiments, is relatively low due to the presence of a lubricatingsurface layer in the presence of humidity. By a “lubricating surfacelayer in the presence of humidity,” it is meant a layer, multiplelayers, a partial layer, or an amount of substance that lubricates thesubstrate such that it has a lower coefficient of friction compared tothe substrate without the material present, when in the presence of someamount of atmospheric humidity.

The specific level of humidity is not regarded as critical, but ingeneral may range from about 1% to 100%, typically about 30% to about70% relative humidity. Relative humidity is the ratio of the water vapordensity (mass per unit volume) to the saturation water vapor density.Relative humidity is approximately the ratio of the actual partialpressure of water vapor to the saturation (maximum) vapor pressure ofwater in air.

The substance that lubricates the substrate is primarily water, but itshould be noted that other components from the environment may bepresent in the lubricating surface layer, including oils, metals, dust,dissolved gases, dissolved aqueous components, suspended non-aqueouscomponents, fragments of debris, fragments of polymers, and so on.

In some embodiments, the material is characterized by a coefficient offriction, measured at 40-55% (e.g. 50%) relative humidity and roomtemperature, less than 0.5, 0.4, 0.3, 0.2, 0.15 or less. In these orother embodiments, the anti-fouling material is characterized by acoefficient of friction, measured at 85-90% relative humidity and roomtemperature, less than 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.15, or less.

The material may be characterized by a surface contact angle of water ofgreater than 90° (hydrophobic). In various embodiments, the material ischaracterized by an effective contact angle of water of about 80°, 85°,90°, 95°, 100°, 105°, 110°, or higher. The material may also behydrophilic, i.e. characterized by an effective contact angle of waterthat is less than 90°.

The material may also be lipophobic or partially lipophobic in someembodiments. In various embodiments, the anti-fouling material ischaracterized by an effective contact angle of hexadecane (as a measureof lipophobicity) of about 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, 90°,or higher.

The material may simultaneously have hydrophobic and lipophobicproperties. In certain embodiments, the material is characterized by aneffective contact angle of water of at least 90° (such as about 95-110°)and simultaneously an effective contact angle of hexadecane of at least60° (such as about 65°). In certain embodiments, the material ischaracterized by an effective contact angle of water of at least 800(such as about 80-85°) and simultaneously an effective contact angle ofhexadecane of at least 700 (such as about 75-80°).

The material may be characterized by a water absorption capacity of atleast 10 wt % water based on total weight of the anti-fouling material.The material is characterized, according to some embodiments, by a waterabsorption capacity of at least 1, 2, 3, 4, 5, 6, 7, 8, or 9 wt % water,preferably at least 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 wt %water, based on total weight of the material.

The material may be characterized by a delay in the formation of ice ona surface of the material. For example, when a material surface is heldat −10° C., the material provided by the invention may be characterizedby an average delay in the formation of ice on the surface of at leastabout 10, 15, 20, 25, 30 minutes, or more.

In various embodiments, the provided material is a coating and/or ispresent at a surface of an object or region. The material may beutilized in relatively small applications, such as lens coatings, or forlarge structures, such as aircraft wings. In principle, the materialcould be present within a bulk region of an object or part, or couldcontain (or be adjacent to) a temporary, protective laminating film forstorage or transport, which is later removed to adhere to the vehicle,for example.

Variations of the invention also provide a precursor material, theprecursor material comprising:

a hardenable material capable of forming a substantially continuousmatrix containing a first component; and

a plurality of inclusions containing a second component, wherein theinclusions are dispersed within the hardenable material,

wherein one of the first component or the second component is alow-surface-energy polymer having a surface energy between about 5 mJ/m²to about 50 mJ/m², and the other of the first component or the secondcomponent is a hygroscopic material containing one or more ionicspecies,

and wherein the low-surface-energy polymer and the hygroscopic materialare chemically connected ionically or covalently.

In some embodiments, the surface energy of the low-surface-energypolymer is between about 10 mJ/m² to about 40 mJ/m², such as about 10,15, 20, 25, 30, 35, or 40, mJ/m². In some embodiments, thelow-surface-energy polymer is a fluoropolymer, such as one selected fromthe group consisting of polyfluoroethers, perfluoropolyethers,polyfluoroacrylates, polyfluorosiloxanes, and combinations thereof.

In some embodiments, the hygroscopic material in the precursor materialis selected from the group consisting of poly(acrylic acid),poly(ethylene glycol), poly(2-hydroxyethyl methacrylate), poly(vinylimidazole), poly(2-methyl-2-oxazoline), poly(2-ethyl-2-oxazoline),poly(vinylpyrolidone), cellulose, modified cellulose, carboxymethylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methylcellulose, hydrogels, PEG diacryalate, monoacrylate, and combinationsthereof. Alternatively, or additionally, the hygroscopic material maycomprise one or more ionic species selected from the group consisting of2,2-bis-(1-(1-methyl imidazolium)-methylpropane-1,3-diol bromide),1,2-bis(2′-hydroxyethyl)imidazolium bromide,(3-hydroxy-2-(hydroxymethyl)-2-methylpropyl)-3-methyl-1H-3λ⁴-imidazol-1-iumbromide, 2,2-bis(hydroxymethyl)butyric acid,N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid,N-methyl-2,2′-iminodiethanol, 3-dimethylamino-1,2-propanediol,2,2-bis(hydroxymethyl)propionic acid, 1,4-bis(2-hydroxyethyl)piperazine,2,6-diaminocaproic acid, N,N-bis(2-hydroxyethyl)glycine,2-hydroxypropanoic acid hemicalsium salt, dimethylolpropionic acid,N-methyldiethanolamine, N-ethyldiethanolamine, N-propyldiethanolamine,N-benzyldiethanolamine, N-t-butyldiethanolamine, bis(2-hydroxyethyl)benzylamine, bis(2-hydroxypropyl) aniline, and homologues, combinations,derivatives, or reaction products thereof.

The low-surface-energy polymer and/or the hygroscopic material may besurface-treated, either prior to introduction into the precursormaterial or prior to conversion of the precursor material to theanti-fouling material.

The precursor material may further contain one or more additionalcomponents selected from the group consisting of a particulate filler, apigment, a dye, a plasticizer, a flame retardant, a flattening agent,and a substrate adhesion promoter. Alternatively, or additionally, suchadditional components may be introduced during the conversion of theprecursor material to the anti-fouling material, or to the anti-foulingmaterial after it is formed.

Specific particulate fillers include, for example, silica, alumina,silicates, talc, aluminosilicates, barium sulfate, mica, diatomite,calcium carbonate, calcium sulfate, carbon, wollastonite, andcombinations thereof. The particulate fillers generally should be in thesize range of about 5 nm to about 2 μm, such as about 20 nm to 100 nm.

The particulate fillers may be surface-modified with a compound selectedfrom the group consisting of fatty acids, silanes, silicones, alkylphosphonates, alkyl phosphonic acids, alkyl carboxylates, andcombinations thereof. Optionally, the fillers may be surface-modifiedwith a hydrophobic material, such as (but not limited to) analkylsilane, a fluoroalkylsilane, and/or an alkyldisilazane (e.g.,hexamethyldisilazane).

Any known methods to fabricate these materials or coatings may beemployed. Notably, these materials or coatings may utilize synthesismethods that enable simultaneous deposition of components or precursormaterials to reduce fabrication cost and time. In particular, thesematerials or coatings may be formed by a one-step process, in someembodiments. In other embodiments, these materials or coatings may beformed by a multiple-step process. Coatings may be cast or sprayed fromorganic solution or from aqueous solution.

The anti-fouling hydrophobic or hydrophilic material, in someembodiments, is formed from a precursor material (or combination ofmaterials) that may be provided, obtained, or fabricated from startingcomponents. The precursor material is capable of hardening or curing insome fashion, to form a substantially continuous matrix along with aplurality of inclusions, dispersed within the matrix. The precursormaterial may be a liquid; a multiphase liquid; a multiphase slurry,emulsion, or suspension; a gel; or a dissolved solid (in solvent), forexample.

The low-surface-energy polymer and the hygroscopic material may be inthe same phase or in different phases. In some embodiments, thelow-surface-energy polymer is in liquid or dissolved form while thehygroscopic material is in dissolved-solid or suspended solid form. Insome embodiments, the low-surface-energy polymer is dissolved-solid orsuspended-solid form while the hygroscopic material is in liquid ordissolved form. In some embodiments, the low-surface-energy polymer andthe hygroscopic material are both in liquid form. In some embodiments,the low-surface-energy polymer and the hygroscopic material are both indissolved (solvent) form.

Some embodiments employ one-shot polymerization to produce a copolymer.In one-shot polymerization, the reactants (e.g., fluoropolymer,isocyanate species, and polyol or polyamine chain extenders orcrosslinkers) are mixed together in the liquid phase in a suitablecontainer, within a mold, or on a substrate, and allowed to reactsimultaneously. No prepolymer is first formed, in such embodiments.

In some variations of the invention, a material or coating precursor isapplied to a substrate (such as a surface of an automobile or aircraft)and allowed to react, cure, or harden to form a final coating, whereinthe material, coating precursor, or final coating contains metal ionsalong with a photosensitizer and/or chemical reducing agent.

In some embodiments, the hygroscopic material is also hardenable, eitheralone or in combination with the low-surface-energy polymer. Forinstance, a low-surface-energy polymer and a hygroscopic polymer mayform a high-molecular-weight block copolymerize and thus harden. Incertain embodiments, the hygroscopic material assists in the curability(hardenability) of the low-surface-energy polymer.

In some embodiments, a precursor material is prepared and then dispensed(deposited) over an area of interest. Any known methods to depositprecursor materials may be employed. A fluid precursor material allowsfor convenient dispensing using spray coating or casting techniques overa large area, such as the scale of a vehicle or aircraft.

The fluid precursor material may be applied to a surface using anycoating technique, such as (but not limited to) spray coating, dipcoating, doctor-blade coating, spin coating, air knife coating, curtaincoating, single and multilayer slide coating, gap coating,knife-over-roll coating, metering rod (Meyer bar) coating, reverse rollcoating, rotary screen coating, extrusion coating, casting, or printing.Because relatively simple coating processes may be employed, rather thanlithography or vacuum-based techniques, the fluid precursor material maybe rapidly sprayed or cast in thin layers over large areas (such asmultiple square meters).

When a solvent or carrier fluid is present in the fluid precursormaterial, the solvent or carrier fluid may include one or more compoundsselected from the group consisting of water, alcohols (such as methanol,ethanol, isopropanol, or tert-butanol), ketones (such as acetone, methylethyl ketone, or methyl isobutyl ketone), hydrocarbons (e.g., toluene),acetates (such as tert-butyl acetate), acids (such as organic acids),bases, and any mixtures thereof. When a solvent or carrier fluid ispresent, it may be in a concentration of from about 10 wt % to about 99wt % or higher, for example.

The precursor material may be converted to an intermediate material orthe final material using any one or more of curing or other chemicalreactions, or separations such as removal of solvent or carrier fluid,monomer, water, or vapor. Curing refers to toughening or hardening of apolymeric material by crosslinking of polymer chains, assisted byelectromagnetic waves, electron beams, heat, and/or chemical additives.Chemical removal may be accomplished by heating/flashing, vacuumextraction, solvent extraction, centrifugation, etc. Physicaltransformations may also be involved to transfer precursor material intoa mold, for example. Additives may be introduced during the hardeningprocess, if desired, to adjust pH, stability, density, viscosity, color,or other properties, for functional, ornamental, safety, or otherreasons.

The overall thickness of the final material or coating may be from about1 μm to about 1 cm or more, such as about 10 μm, 20 μm, 25 μm, 30 μm, 40μm, 50 μm, 75 μm, 100 μm, 500 μm, 1 mm, 1 cm, or 10 cm. Relatively thickcoatings offer good durability and mechanical properties, such as impactresistance, while preferably being relatively lightweight.

EXAMPLES

Materials. Poly(ethylene glycol) (PEG) with molecular weight (M_(n)) of3,400 g/mol, 4,4′-methylenebis(cyclohexyl isocyanate) (HMDI),1,4-butanediol (BD), dibutyltin dilaurate (DBTDL), and2,2-bis(hydroxymethyl)propionic acid are purchased from Aldrich.Fluorolink materials are purchased from Solvay Specialty Polymers. Allchemicals are used as received without further purification.

Example A Fluoropolymer Control

Fluorolink D4000 perfluoropolyether (4 g) is charged to a vial followedby HMDI (0.786 g) and dibutyltin dilaurate (0.02%). A small PTFE-coatedstir bar is introduced and the vial is placed in a 100° C. oil bath tostir. The reaction is vortexed aggressively after achieving atemperature of 100° C., and then left to stir for 1 hour. After thisstep, the resin is poured into a 3″×3″ PTFE mold to flash off solventand cure the film at room temperature overnight.

Example B Thermoplastic Polymer without Ionic Species

Hydroxyl-terminated poly(perfluoropolyether) (9.00 g, 3.73 mmol,Fluorolink 5147x) is placed in a 3-neck roundbottom flask that containsan inlet for argon and equipped with an overhead stirrer (Teflon shaftand blade). While stirring, 4,4′-methylenebis(cyclohexyl isocyanate)(4.89 g, 18.66 mmol) is added to the solution and the flask is placed inan oil bath at 100° C. Dibutyltin dilaurate (0.02 wt %) is then added tothe solution using a micropipette and the polymerization reaction isallowed to proceed.

After 1 hr, the prepolymer is then allowed to cool down to roomtemperature. The prepolymer is diluted with tetrahydrofuran (15 mL) andplaced in a centrifugal mixer (FlackTek DAC 600).

In a separate vial, chain extender 1,4-butanediol (1.35 g, 14.98 mmol)is weighed and diluted with tetrahydrofuran (0.5 mL). The two solutionsare combined in a centrifugal mixer and mixed at 2300 rpm for 15seconds. The polymer is cast from solution or sprayed using an airbrushto create a polyurethane film/coating.

Example C Thermoplastic Polymer with Ionic Species

Hydroxyl-terminated poly(perfluoropolyether) (9.00 g, 3.73 mmol,Fluorolink 5147x) is placed in a 3-neck roundbottom flask that containsan inlet for argon and equipped with an overhead stirrer (Teflon shaftand blade). While stirring, 4,4′-methylenebis(cyclohexyl isocyanate)(4.89 g, 18.66 mmol) is added to the solution and the flask is placed inan oil bath at 100° C. Dibutyltin dilaurate (0.02 wt %) catalyst is thenadded to the solution using a micropipette and the polymerizationreaction is allowed to proceed.

After 1 hr, the ionic species precursor 2,2-bis(hydroxymethyl)propionicacid (0.50 g, 3.74 mmol) is added to the stirring solution and allowedto dissolve and react for 1 hr. The prepolymer is then allowed to cooldown to room temperature. The prepolymer is diluted with tetrahydrofuran(15 mL) and placed in a plastic mixing container for centrifugal mixing.

In a separate vial, chain extender 1,4-butanediol (1.01 g, 11.21 mmol)is weighed and diluted with tetrahydrofuran (0.5 mL). The two solutionsare combined in mixing centrifugal mixer and mixed at 2300 rpm for 15seconds to form polymer. The polymer is cast from solution or sprayedusing an airbrush to create a polyurethane film/coating.

Multiple samples are prepared, as follows. Sample C1 is unsoaked, sampleC2 is soaked in deionized water, sample C3 is soaked in 0.01 M HCl, andsample C4 is soaked in 0.01 M Ca(OH)₂. Samples C1, C2, C3, and C4 arethen tested in accordance with Example F (friction testing) below.

Example D High-Molecular Weight PEG Combined with PFPE/PEG Triblockwithout Ionic Species

Hydroxyl-terminated poly(ethylene glycol) (M_(n)=3400, 2.50 g, 0.74mmol) is placed in a 3-neck roundbottom flask that contains an inlet forargon and equipped with an overhead stirrer (Teflon shaft and blade).While stirring, 4,4′-methylenebis(cyclohexyl isocyanate) (3.72 g, 14.20mmol) is added to the solution and the flask is placed in an oil bath at100° C. Dibutyltin dilaurate (0.02 wt %) is then added to the solutionusing a micropipette and the polymerization reaction is allowed toproceed.

After 1 hr, Fluorolink E10-H (2.78 g, 1.40 mmol) is added to thestirring solution and allowed to react for 2 hr at 100° C. Theprepolymer is then allowed to cool down to room temperature. Theprepolymer is diluted with tetrahydrofuran (9.15 mL) and placed in aplastic mixing cup before inserting into the centrifugal mixer.

In a separate vial, 1,4-butanediol (0.77 g, 8.54 mmol) is weighed anddiluted with tetrahydrofuran (0.5 mL). The two solutions are combined ina centrifugal mixer and mixed at 2300 rpm for 15 seconds. The polymer iscast from solution or sprayed using an airbrush to create a polyurethanefilm/coating.

Multiple samples are prepared, as follows. Sample D1 is unsoaked, sampleD2 is soaked in demonized water, and sample D3 is soaked in NaOH atpH=14. Samples D1, D2, and D3 are then tested in accordance with ExampleF (friction testing) below.

Example E High-Molecular Weight PEG Combined with PFPE/PEG Triblock withIonic Species

Hydroxyl-terminated poly(ethylene glycol) (2.50 g, 0.74 mmol) is placedin a 3-neck roundbottom flask that contains an inlet for argon andequipped with an overhead stirrer (Teflon shaft and blade). Whilestirring, 4,4′-methylenebis(cyclohexyl isocyanate) (4.49 g, 17.14 mmol)is added to the solution and the flask is placed in an oil bath at 100°C. Dibutyltin dilaurate (0.02 wt %) is then added to the solution usinga micropipette and the polymerization reaction is allowed to proceed.

After 1 hr, the ionic species precursor 2,2-bis(hydroxymethyl)propionicacid (0.79 g, 5.89 mmol) is added to the stirring solution and allowedto dissolve and react for 1 hr. After 1 hr, Fluorolink E10-H (2.78 g,1.40 mmol) is added to the stirring solution and allowed to react for 2hr at 100° C. The prepolymer is then allowed to cool down to roomtemperature. The prepolymer is diluted with tetrahydrofuran (12.75 mL)and placed in a plastic mixing container for centrifugal mixing.

In a separate vial, 1,4-butanediol (0.77 g, 8.54 mmol) is weighed anddiluted with tetrahydrofuran (0.5 mL). The two solutions are combined ina centrifugal mixer and mixed at 2300 rpm for 15 seconds. The polymer iscast from solution or sprayed using an airbrush to create a polyurethanefilm/coating.

Multiple samples are prepared, as follows. Sample E1 is unsoaked, sampleE2 is soaked in deionized water, sample E3 is soaked in NaOH at pH=14,sample E4 is soaked in HCl at pH=2, and sample E5 includes copperacetate exposure during synthesis of the sample. Samples E1, E2, E3, E4,and E5 are then tested in accordance with Example F (friction testing)below.

Example F Friction Testing of Samples

The change in friction in response to humidity is tested by firstequilibrating the coating samples of Examples A, B, C, D, and E atambient (40-55%) relative humidity or 85-90% relative humidity in ahumidity-controlled chamber. Then the coating samples are placed on avariable-angle stage and the angle is increased until a 5-gramcylindrical mass slides along the sample surface. The sliding angle isused to determine the friction constant (coefficient of friction).

The friction change is shown for the coating samples of Examples A-E inthe table of FIG. 3. Contact angles of water are also shown for samplesA, C1, C2, C3, C4, E1, E2, E3, E4, and E5. From the table in FIG. 3,sliding and coefficient-of-friction performance with differentembodiments of the technology versus controls can be observed.

The initial control (sample B) is produced from a PFPE and isocyanateprepolymer mixture that is cast from solution and allowed to cure underthe influence of atmospheric moisture. This composition has nohygroscopic component and shows a relatively higher coefficient offriction compared to other test samples at 85-90% relative humidity.Under the influence of increasing humidity, the coefficient of frictionincreased.

Examples B and C—linear thermoplastic polymer without and with ionicspecies, respectively—demonstrate the benefits of ionic charge oncoefficient of friction and its behavior under increasing humidity.Example B incorporates a triblock precursor molecule with PFPE as thecentral block and poly(ethylene glycol) blocks on the terminal ends.According to the data for sample B, a coating from this mixture produceslow coefficient of friction values but exhibits an increase incoefficient of friction with increased humidity.

The opposite is the case when ionic monomer species are introduced intothe chain backbone (Example C). Coefficient of friction in samples C1,C2, C3, or C4 begins at 0.19 near 50% relative humidity and decreases orstays constant with increasing humidity. This data also indicates that,at constant relative humidity, the coefficient of friction is reducedafter soaking the coating in water, HCl or Ca salt solutions. Thecoefficient of friction is as low as 0.13, for a 0.01 M Ca(OH)₂ soak ofthe coating then exposed to 85-90% relative humidity for the frictiontest.

Examples D and E use high-molecular-weight PEG as a first soft segmentcombined with a PFPE/PEG triblock as a second soft segment. Example Eincorporates ionic species, while Example D is a control sample with noionic species along the backbone. The system starts off at a highercoefficient of friction of 0.38 at 50% relative humidity, and withelevated humidity, the coefficient of friction increase to 0.62 (sampleD1). Soaking in deionized water reverses this trend and causes a drop incoefficient of friction (sample D2). However, exposure to basic solutionconditions creates a situation that lowers coefficient of friction at50% relative humidity while giving a dramatic (nearly two-fold) increasein coefficient of friction at 90% relative humidity (sample D3).

When carboxylic acid groups are incorporated into the backbone of thesepolymers (Example E), an overall decrease in the magnitude of thecoefficient of friction is observed for each sample compared to thecontrol sample, whether unsoaked (E1 versus D1), soaked in water (E2versus D2), or soaked in basic solution (E3 versus D3). The relativeincrease in coefficient of friction with increased humidity is reducedfor both the unsoaked and base-soaked sample.

Overall, these systems demonstrate the ability to be positivelyinfluenced through lower coefficient-of-friction performance by theincorporation of ionic species (free acid or charged species) along thechain backbone.

Example G Chemical and Photoreduction of Metal Ions

In this example, polymer films (such as the Example E material) aresoaked in solutions of calcium hydroxide, copper (II) acetate, or iron(II) acetate to incorporate the metal cations into the polymer network.The ions are reduced chemically, with a reducing agent such as sodiumborohydride or hydrazine, or with UV-light. In the latter system, themetal crosslinked polymer film is subsequently soaked in an aqueoussolution of tris(bipyridine)ruthenium(II) chloride, [Ru(bpy)₃]Cl₂, anddimethylamine. A broadband mercury lamp is used to irradiate the polymerfilm and induce a photoactivated reduction. Mechanical properties aremeasured using dynamic mechanical analysis.

Urethane-based block copolymers are synthesized using a multi-stepprocedure. First, a hygroscopic polyol is combined with a coupling agentto form oligomers. An ionic precursor containing diol functionality isnext added to the reaction mixture and allowed to dissolve and extendthe chains further. Once fully dissolved, the second polyol precursor isadded to the reaction mixture to complete the prepolymer synthesis. Themixture is dispersed in a solvent containing a curative and may be castor spray-applied with a low-volume, low-pressure air-brush (IwataEclipse). The film is allowed to dry overnight followed by a finalthermal cure step. This results in a tough free-standing film that canbe further tested.

The material properties are analyzed using dynamic mechanical analysis(DMA) instrument (Q800, TA Instruments). Modulus versus temperature isscreened (1 Hz, 3° C./min) along with stress-versus-strain response ofthe coating films (5%/min). Large specimens are cut into dog bones andtested for tensile strength and elongation using an Instron (Instron5565, 10 mm/min).

The reduction of metal ions in solution is followed usingultraviolet-visible spectroscopy (Perkin Elmer Lambda 950). This isaccomplished by monitoring the change in absorbance spectrum as valencestate of the metal ions changed.

Polymer films are soaked in solutions of calcium hydroxide, copper (II)acetate, or iron (II) acetate to incorporate the metal cations into thepolymer network. The ions are reduced chemically, with a reducing agentsuch as sodium borohydride hydrazine, or with UV-light. In the lattersystem, the metal-crosslinked polymer film is subsequently soaked in anaqueous solution of tris(bipyridine)ruthenium(II) ([Ru(bpy)₃]²⁺)chloride and dimethylamine. A broadband mercury lamp is used toirradiate the polymer film and induce a photoactivated reduction.

Metal ions that have the ability to undergo photoreduction and can beincorporated into our polymer network are identified. Ions are selectedwith desirable redox potentials with respect to photosensitive dyes.Photosensitive dyes have the ability to absorb visible light, promotingan electron from ground state to an excited state. These electrons canthen be used to reduce other elements such as metal ions. The metal ionsof nickel (Ni), iron (Fe), and copper (Cu) are chosen in this exampledue to their positive reduction potentials. Using ultraviolet-visible(UV-Vis) spectroscopy to monitor the reduction, metal ions are placed insolution with a ruthenium-based photosensitive dye and an electrondonor.

FIG. 4 shows UV-Vis spectrum of the reduction of Fe³⁺ to Fe²⁺ in thepresence of ruthenium dye and light. A copper solution before and afterlight exposure reveals reduced Cu nanoparticles precipitated out ofsolution. Results from this experiment show that both Fe³⁺ and Cu²⁺could be reduced with this method in solution. These metals areeffective for light-induced crosslinking.

Example H Reversible Crosslinking Using Calcium Ions

In order to test the crosslinking ability of polymer films (such asfilms made from the Example E material) with metal ions, films aresoaked in calcium hydroxide (Ca(OH)2) solutions. Calcium ions are knownto bind very tightly to carboxylic acid groups. To test for reversiblecrosslinking within these polymer films, the samples are then soaked inhydrochloric acid solutions to protonate the carboxylic acid groups forremoval of Ca²⁺ ions. Mechanical properties are measured using dynamicmechanical analysis.

Charged constituents in polymers are both water-absorbing and bound withcounterions, and when incorporated into polymer systems, the chargedconstituents have the ability to change the bulk and surface propertiesin response to materials bound to the network. In this example, thesecharged constituents are incorporated into the polymer coating todemonstrate reversible interchain crosslinking. Upon addition into thepolymer, the functional groups are protonated and uncharged, allowingthe network to be held together by the hydrogen bonding in hard-segmentdomains of concentrated urethane bonds.

In order to test the crosslinking ability of these polymer films withmetal ions, films are soaked in calcium hydroxide (Ca(OH)₂) solutions.To prove reversible crosslinking, the polymer samples are then soaked inhydrochloric acid solutions to protonate the carboxylic acid groups forremoval of Ca²⁺ ions. DMA screens of modulus versus temperature provideinformation on rigidity of the samples as well as transitiontemperatures (T_(g) and T_(m)).

FIG. 5 shows a full cycle of reversible crosslinking demonstrated usingCa²⁺ as a model metal ion, with sequential Ca²⁺ and HCl soaks. At roomtemperature, the film modulus starts at 13 MPa for the untreated filmand 132 MPa for the Ca²⁺-soaked film, giving a 10-fold increase inmodulus. Another notable difference from this data is themelting/softening temperature of the untreated and Ca²⁺-soaked films.The hydrogen bonding of urethane groups destabilizes with heat, and theuntreated film melts long before reaching 150° C. On the other hand, theCa²⁺-soaked film maintains a modulus of 14 MPa at 150° C., indicative ofion-mediated crosslinking, giving higher thermal stability.

The same film is then soaked in acidic solution (HCl) to protonate thefunctional groups in order to destabilize crosslinking and remove Ca²⁺,which results in complete reversal to a lower modulus and meltingtemperature. In order to prove reversibility, the film is re-soaked inCa²⁺ solution, regaining rigidity and thermal stability, and overlappingwith the previous Ca²⁺-soaked modulus versus temperature curve in FIG.5.

Example I Reversible Crosslinking Using Copper Ions

In this example, films are prepared and crosslinked using metal ionswith proven reducibility with photosensitive dyes. Embedded metal ionsare tested for chemical and light reduction within film and propertiesanalyzed by DMA analysis. Following a similar protocol to Ca²⁺crosslinking (Example H), the films are soaked in a Cu²⁺ solution.

It is experimentally found that Cu²⁺ induces a higher crosslinkingdensity, reducing the flexibility of the film versus the highly flexibleuntreated film. It required 10× the amount of stress to strain the filmby 30% elongation after Cu²⁺ exposure (FIG. 6).

When the metal ions are chemically reduced, the film's initialproperties are almost recovered with only 2× the amount of stress neededfor 30% elongation, as compared to the film before Cu²⁺ exposure.

To test light-induced reduction, Cu²⁺-embedded films are soaked in asolution containing photosensitizing dye and electron donors. Afterirradiating with light, the film is tested and shows almost a 50%reduction in the amount of stress needed to elongate 30%. The tests alsoshowed that the ions in the film are reduced with visible light whensoaked with photosensitizing dye.

FIG. 6 shows the stress required for 30% elongation whencharged-constituent-containing polymer films are crosslinked with Cu²⁺ions and after chemical and light reduction.

Variations of the invention provide film, coating, or object containingany of the disclosed polymer compositions. The film, coating, or objectmay be characterized as reversible, re-mendable, self-healing,mechanically adjustable, and/or thermoplastic/thermoset-switchable, invarious embodiments.

Practical applications for the present invention include, but are notlimited to, vehicle windows, cameras, optical lenses, filters,instruments, sensors, eyeglasses, aircraft surfaces, satellites, andweapon systems. For example, automotive applications can utilize thesecoatings to prevent the formation of ice or debris on back-up cameralenses or back-up sensors. The principles taught herein may also beapplied to self-cleaning materials, anti-adhesive coatings,corrosion-free coatings, etc.

In this detailed description, reference has been made to multipleembodiments and to the accompanying drawings in which are shown by wayof illustration specific exemplary embodiments of the invention. Theseembodiments are described in sufficient detail to enable those skilledin the art to practice the invention, and it is to be understood thatmodifications to the various disclosed embodiments may be made by askilled artisan.

Where methods and steps described above indicate certain eventsoccurring in certain order, those of ordinary skill in the art willrecognize that the ordering of certain steps may be modified and thatsuch modifications are in accordance with the variations of theinvention. Additionally, certain steps may be performed concurrently ina parallel process when possible, as well as performed sequentially.

All publications, patents, and patent applications cited in thisspecification are herein incorporated by reference in their entirety asif each publication, patent, or patent application were specifically andindividually put forth herein.

The embodiments, variations, and figures described above should providean indication of the utility and versatility of the present invention.Other embodiments that do not provide all of the features and advantagesset forth herein may also be utilized, without departing from the spiritand scope of the present invention. Such modifications and variationsare considered to be within the scope of the invention defined by theclaims.

What is claimed is:
 1. A polymer composition comprising: (a) a polymermatrix containing one or more ionic species, wherein said polymer matrixcontains a substantially continuous matrix containing a first component;and, dispersed within said matrix, a plurality of inclusions containinga second component that is chemically different than said firstcomponent, wherein one of said first component or said second componentis a first polymer having a surface energy between about 5 mJ/m² toabout 50 mJ/m², and the other of said first component or said secondcomponent is a second polymer containing said one or more ionic species,wherein said first polymer and said second polymer are chemicallyconnected ionically or covalently, and wherein said first polymer is afluoropolymer selected from the group consisting of polyfluoroethers,perfluoropolyethers, polyfluoroacrylates, polyfluorosiloxanes, andcombinations thereof; (b) one or more photosensitizers selected from thegroup consisting of organic photosensitizers, inorganicphotosensitizers, and combinations thereof; and (c) one or more metalions having a first oxidation state and a second oxidation state,wherein said first oxidation state reversibly changes to said secondoxidation state when in the presence of said photosensitizers and light,wherein said metal ions, in said first oxidation state, have a firstcoordination number with said ionic species, wherein said metal ions, insaid second oxidation state, have a second coordination number with saidionic species, and wherein said first coordination number is greaterthan said second coordination number.
 2. The polymer composition ofclaim 1, wherein said second oxidation state is one unit of charge lessthan said first oxidation state.
 3. The polymer composition of claim 1,wherein said second oxidation state is two or more units of charge lessthan said first oxidation state.
 4. The polymer composition of claim 1,wherein said metal ions are selected from the group consisting of ionsof Ni, Fe, Cu, Hg, Cd, and combinations thereof.
 5. The polymercomposition of claim 1, wherein said photosensitizers include at leastone organic photosensitizer.
 6. The polymer composition of claim 5,wherein said organic photosensitizer is a photosensitive organic dye. 7.The polymer composition of claim 1, wherein said photosensitizersinclude at least one inorganic photosensitizer.
 8. The polymercomposition of claim 1, wherein said second polymer is selected from thegroup consisting of polyethers, polyesters, polysiloxanes,polyelectrolytes, and combinations thereof.
 9. The polymer compositionof claim 1, wherein said second polymer includes a material selectedfrom the group consisting of poly(acrylic acid), poly(ethylene glycol),poly(2-hydroxyethyl methacrylate), poly(vinyl imidazole),poly(2-methyl-2-oxazoline), poly(2-ethyl-2-oxazoline),poly(vinylpyrolidone), cellulose, modified cellulose, carboxymethylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methylcellulose, hydrogels, PEG diacryalate, monoacrylate, and combinationsthereof.
 10. The polymer composition of claim 1, wherein said ionicspecies includes one or more species selected from the group consistingof an ionizable salt, an ionizable molecule, a zwitterionic component, apolyelectrolyte, an ionomer, and combinations thereof.
 11. The polymercomposition of claim 1, wherein said ionic species is selected from thegroup consisting of (2,2-bis-(1-(1-methylimidazolium)-methylpropane-1,3-diol bromide),1,2-bis(2′-hydroxyethyl)imidazolium bromide,(3-hydroxy-2-(hydroxymethyl)-2-methylpropyl)-3-methyl-1H-3λ⁴-imidazol-1-iumbromide, 2,2-bis(hydroxymethyl)butyric acid,N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid,N-methyl-2,2′-iminodiethanol, 3-dimethylamino-1,2-propanediol,2,2-bis(hydroxymethyl)propionic acid, 1,4-bis(2-hydroxyethyl)piperazine,2,6-diaminocaproic acid, N,N-bis(2-hydroxyethyl)glycine,2-hydroxypropanoic acid hemicalsium salt, dimethylolpropionic acid,N-methyldiethanolamine, N-ethyldiethanolamine, N-propyldiethanolamine,N-benzyldiethanolamine, N-t-butyldiethanolamine, bis(2-hydroxyethyl)benzylamine, bis(2-hydroxypropyl) aniline, and homologues, combinations,derivatives, or reaction products thereof.
 12. The polymer compositionof claim 1, wherein said second polymer consists essentially of saidionic species.
 13. The polymer composition of claim 1, wherein saidfirst polymer and said second polymer are covalently connected in ablock copolymer.
 14. The polymer composition of claim 1, wherein saidpolymer composition further contains one or more additional componentsselected from the group consisting of a particulate filler, a substrateadhesion promoter, a pigment, a coloring agent, a plasticizer, aflattening agent, and a flame retardant.
 15. A polymer compositioncomprising: (a) a polymer matrix containing one or more ionic species;(b) one or more photosensitizers; and (c) one or more metal ions capableof reversibly changing from a first oxidation state to a secondoxidation state when in the presence of said photosensitizers and light,wherein said metal ions, in said first oxidation state, have a firstcoordination number with said ionic species, wherein said metal ions, insaid second oxidation state, have a second coordination number with saidionic species, wherein said first coordination number is greater thansaid second coordination number, and wherein said polymer matrixcontains a segmented copolymer comprising: one or more soft segmentsselected from fluoropolymers having an average molecular weight fromabout 500 g/mol to about 20,000 g/mol, wherein said fluoropolymers are(α,ω)-hydroxyl-terminated and/or (α,ω)-amine-terminated, and either: (i)wherein said soft segments contain said one or more ionic species; or(ii) one or more copolymer chains that are distinct from said softsegments, wherein said copolymer chains contain said one or more ionicspecies; one or more isocyanate species, or a reacted form thereof,possessing an isocyanate functionality of 2 or greater; and one or morepolyol or polyamine chain extenders or crosslinkers, or a reacted formthereof.
 16. The polymer composition of claim 15, wherein saidfluoropolymers are selected from the group consisting ofpolyfluoroethers, perfluoropolyethers, polyfluoroacrylates,polyfluorosiloxanes, and combinations thereof.
 17. The polymercomposition of claim 15, wherein said segmented copolymer furthercomprises one or more second soft segments selected from polyesters orpolyethers, wherein said polyesters or polyethers are(α,ω)-hydroxyl-terminated and/or (α,ω)-amine-terminated.
 18. The polymercomposition of claim 17, wherein said polyesters or polyethers areselected from the group consisting of poly(oxymethylene), poly(ethyleneglycol), poly(propylene glycol), poly(tetrahydrofuran), poly(glycolicacid), poly(caprolactone), poly(ethylene adipate),poly(hydroxybutyrate), poly(hydroxyalkanoate), and combinations thereof.19. The polymer composition of claim 15, wherein said ionic speciesincludes one or more species selected from the group consisting of anionizable salt, an ionizable molecule, a zwitterionic component, apolyelectrolyte, an ionomer, and combinations thereof.
 20. The polymercomposition of claim 19, wherein said ionic species is selected from thegroup consisting of (2,2-bis-(1-(1-methylimidazolium)-methylpropane-1,3-diol bromide),1,2-bis(2′-hydroxyethyl)imidazolium bromide,(3-hydroxy-2-(hydroxymethyl)-2-methylpropyl)-3-methyl-1H-3λ⁴-imidazol-1-iumbromide, 2,2-bis(hydroxymethyl)butyric acid,N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid,N-methyl-2,2′-iminodiethanol, 3-dimethylamino-1,2-propanediol,2,2-bis(hydroxymethyl)propionic acid, 1,4-bis(2-hydroxyethyl)piperazine,2,6-diaminocaproic acid, N,N-bis(2-hydroxyethyl)glycine,2-hydroxypropanoic acid hemicalsium salt, dimethylolpropionic acid,N-methyldiethanolamine, N-ethyldiethanolamine, N-propyldiethanolamine,N-benzyldiethanolamine, N-t-butyldiethanolamine, bis(2-hydroxyethyl)benzylamine, bis(2-hydroxypropyl) aniline, and homologues, combinations,derivatives, or reaction products thereof.
 21. The polymer compositionof claim 15, wherein said isocyanate species is selected from the groupconsisting of4,4′-methylenebis(cyclohexyl isocyanate), hexamethylenediisocyanate, cycloalkyl-based diisocyanates, tolylene-2,4-diisocyanate,4,4′-methylenebis(phenyl isocyanate), isophorone diisocyanate, andcombinations or derivatives thereof.
 22. The polymer composition ofclaim 15, wherein said polyol or polyamine chain extenders orcrosslinkers have an average functionality of at least
 3. 23. Thepolymer composition of claim 15, wherein said one or more polyol orpolyamine chain extenders or crosslinkers are selected from the groupconsisting of 1,3-butanediol, 1,4-butanediol, 1,3-propanediol,1,2-ethanediol, diethylene glycol, triethylene glycol, tetraethyleneglycol, propylene glycol, dipropylene glycol, tripropylene glycol,neopentyl glycol, 1,6-hexane diol, 1,4-cyclohexanedimethanol, ethanolamine, diethanol amine, methyldiethanolamine, phenyldiethanolamine,glycerol, trimethylolpropane, 1,2,6-hexanetriol, triethanolamine,pentaerythritol, ethylenediamine,1,3-propanediamine, 1,4-buatendiamine,diethyltoluenediamine, dimethylthiotoluenediamine, isophoronediamine,diaminocyclohexane, N,N,N′,N′-tetrakis (2-hydroxypropyl)ethylenediamine, and homologues, combinations, derivatives, or reactionproducts thereof.
 24. A film or coating containing the polymercomposition of claim
 1. 25. A polymer composition comprising: (a) apolymer matrix containing a first polymer, a second polymer, and one ormore ionic species, wherein said first polymer is a fluoropolymerselected from the group consisting of polyfluoroethers,perfluoropolyethers, polyfluoroacrylates, polyfluorosiloxanes, andcombinations thereof; (b) one or more photosensitizers selected from thegroup consisting of organic photosensitizers, inorganicphotosensitizers, and combinations thereof; and (c) one or more metalions having a first oxidation state and a second oxidation state that isdifferent than said first oxidation state, wherein said first oxidationstate is ±1, ±2, or ±3, wherein said second oxidation state is ±1, ±2,or ±3, and wherein said first oxidation state reversibly changes to saidsecond oxidation state when in the presence of said photosensitizers andlight, wherein said metal ions, in said first oxidation state, have afirst coordination number with said ionic species, wherein said metalions, in said second oxidation state, have a second coordination numberwith said ionic species, and wherein said first coordination number isgreater than said second coordination number.
 26. The polymercomposition of claim 25, wherein said second polymer is selected fromthe group consisting of polyethers, polyesters, polysiloxanes,polyelectrolytes, and combinations thereof.
 27. The polymer compositionof claim 25, wherein said first polymer and said second polymer arecovalently connected in a block copolymer.